4
Placing a hand on his chest and taking short, shallow breaths, Yuma looked around the game room. Heavy snow was falling across the glass of the Tower, and the room was slowly dimming as the sun set.
According to the grandfather clock, it was almost 5:00 P.M. Yuma stroked the barrel of the shotgun in his hands. The cold, hard feeling was comforting to him, setting his nerves at ease.
After preparing in the display room, Yuma had descended the hidden stairway to the power room, and from there gone back up the normal stairs to the first floor. There was no one there; everyone was holed up in their rooms. Yuma went to the game room and stood by the entrance, preparing himself for the final battle.
Now, the climax had come. It was time to lower the curtain on the tragedy that had unfolded in that spire of glass.
Steeling himself, Yuma hit the button of the fire alarm on the wall. The moment he did, a loud siren rang out. The sprinklers didn't go off, though. Maybe they were programmed to only go off if they actually detected a fire.
Yuma ran from the game room into the dining room next door, observing through the gap in the door.
“There is a fire in the game room. There is a fire in the game room. Evacuate at once.”
Sakyo, Kuruma, Sakaizumi, Yumeyomi, and finally Tsukiyo all appeared and gathered in front of the game room.
“It doesn't look like there's any fire.”
Opening the door and peering into the game room, Kuruma visibly relaxed.
“Then why did the fire alarm go off!? And why haven't the police arrived yet? It's already evening!”
“Please stay calm, Ms. Yumeyomi. They'll be here soon.”
“Soon? When is 'soon'!? I want to get out of this tower as soon as possible!”
As Sakyo tried to calm the hysterical Yumeyomi, Tsukiyo silently stared into the game room.
“At a glance, there aren't any signs of there having ever been a fire. Since the fire alarm went off anyway, that means either there was a malfunction... or someone hit the alarm.”
“What!? Who could have done that? Was someone locked in the dungeon after all!?”
Sakaizumi was terrified.
“No, that isn't it. The only person who would do something like this...”
Yuma stepped out of the dining room.
“Yes, it was me.”
Everyone looked shocked even before they noticed the shotgun in his hands. When they did, they quailed with fear. Everyone except Tsukiyo, who showed him a serene smile.
“Hello, Yuma. How did you get out of the display room?”
“I'm glad you asked, because I'd love to tell you all. Sorry, everyone, but could you go to the game room for a moment? This will probably take a while.”
“Don't screw with me!” Sakaizumi yelled. “I'm not listening to a murderer. You think a toy like that will-”
Instantly, Yuma pointed the gun at the pillar in the center of the hall and pulled the trigger. An explosion so loud it hurt his ears and a shockwave far stronger than he'd expected ran through him. A sizable chunk of the colored glass around the pillar shattered and fell to the floor, and the smell of gunpowder filled the air.
“This isn't a toy, Sakaizumi. It's a real gun, and as you just said, I'm a murderer. I won't hesitate to shoot you if you force my hand. Got that? Then just go to the game room.”
Yuma nervously waited for Sakaizumi and the others to react. He was bluffing, of course. There was no way he could shoot them. If anyone ran at him, it would all be over. The atmosphere in the room was strained to the limit. Sakaizumi and Sakyo began to lean forward.
“It's fine, isn't it?”
Just as something was about to snap, Tsukiyo asked, light as air.
“The police are running late, so I've just been sitting here killing time. It wouldn't be the worst thing in the world to listen to his story. If we sit and listen, you guarantee our safety, Yuma?”
“Yes, I promise.”
When Yuma nodded, Tsukiyo seized the initiative and said “Okay then, let's go, everyone,” and entered the game room. After a moment's hesitation, Sakyo and Sakaizumi seemed to lose their wills and followed suit.
“If you've gone this far, you must have something very interesting to share.”
Tsukiyo turned back and gave him a sidelong glance.
“Of course.”
“I'm looking forward to hearing, ex-Watson.”
Tsukiyo raised the corner of her lip in a sarcastic grin. After confirming that all five of them had entered the game room, Yuma followed behind them, gun in hand.
“Everyone, please go to the far side of the sofa and stand by the window.”
Seeing all five of them obediently follow his instructions, Yuma inwardly sighed in relief. With the sofa between them and him, nobody could suddenly jump him. He'd cleared the first hurdle.
“Dr. Ichijou,” Kuruma admonished him. “There's no point to all this. The police will be here soon. There's no way out for you. You shouldn't commit any more crimes.”
“I have no intention of running away. I just want the truth of what happened in this Tower known.”
“The truth? What are you saying? You admitted that you poisoned Kozushima and tried to pin the blame on Kagami. Are you saying that was wrong?”
“No, it isn't wrong. I did give Mr. Kozushima that capsule, and I slipped the pill case with the rest of them into Mr. Kagami's pocket.”
Kuruma started “Then-”, but Yuma held out a hand and stopped him.
“But I've realized something. There is another side to this incident, hidden behind this Tower.”
“Another side?”
Kuruma sounded suspicious. Tsukiyo took a step forward, face grim.
“Yuma, are you accusing me of having been wrong? You think I, a great detective, presented an incorrect theory?”
“No, not at all,” Yuma shook his head. “Your reasoning was flawless. As a great detective, you were able to solve The Glass House Murders.”
“What are you talking about? If the case was solved, than it's over. We know the truth behind all the incidents and the identity of the culprits. Just what else could you have to add!?”
Yumeyomi raised her voice.
“To explain that, I first need to tell you how I managed to escape from the display room.”
Yuma spoke calmly. Sakyo pointed at him.
“That's right, how did you open that door? It can't be unlocked from the inside. It's what you'd call...”
“A locked room.”
Yuma muttered to himself, and Sakyo started.
“Yes, the display room was a perfect locked room. How do you think I was able to escape? What sort of trick did I use?”
No one answered Yuma's question. Yuma approached the projector on the floor and switched it on, then took out his smartphone from his pocket and turned off all the lights in the room. He had brought the projector from the dining room where Tsukiyo had left it beforehand.
In the dimly lit game room, an image was projected of the hidden door in the floor of the display room, open to reveal the glass stairs underneath. He had taken the picture before coming down.
“It's simple. There was actually a hidden door in the display room, containing a secret spiral staircase that led down to the basement.”
Seeing the deep wrinkles that formed on Kuruma's brow, Yuma shrugged.
“I understand, Mr. Kuruma. It's the dirtiest trick in the game. You think you're dealing with a locked room, then it turns out there was a secret passage the whole time. But it's not like there were no clues. Mr. Kozushima always told people the Glass Tower is an exact replicate of a TRIDENT, the device he invented that delivers DNA into cell nuclei. If that's the case, then there should be two spiral staircases side by side to replicate the double helix shape of the DNA, wrapped around the center of the glass spire.”
“So, what? The hidden stairway is the other side of the incident?”
Sakaizumi was annoyed.
“It's a glimpse of it. By the way, Ms. Yumeyomi.”
Yuma suddenly pointed at Yumeyomi, who shouted “W-What!?”
“Ms. Yumeyomi, from the beginning, you've been saying that there was some sort of evil entity hiding in the Tower, haven't you?”
“...And what if I have?”
Yuma tapped at his phone and said “Look at this.” Images of the window to the First room and the hidden door behind the bookshelf were projected onto the white wall one after another.
Everyone stared at the images and groaned.
“As you can see, the mirror in the First room is one way, and through it, the inside of the room is visible from the hidden stairway. And if you enter the correct password, the bookshelf will move, allowing you to enter the room.”
“I-Is it... only in the First room...?”
Yumeyomi asked, pointing a shaking finger at the image.
“No, it isn't. The same setup is present in all of the guest rooms.”
Yumeyomi covered her mouth with both hands and shrieked.
“Yes, you really were being watched by someone. And that ominous presence you felt on the spiral staircase was someone moving on the hidden stairs on the other side of the glass wall.”
Yumeyomi's jaw dropped. She was speechless. The other listeners were also frozen in shock. The sun had completely set, and silence and darkness filled the game room. Yuma hit the switch on the wall to turn on the chandelier. A dazzlingly warm light filled his eyes, which had grown accustomed to the darkness.
“So what is it you mean to say?” Sakyo asked, breathing heavily. “I don't understand what it is you're getting at, but even if there is a hidden stairway, it doesn't change the fact that you and Mr. Kagami are the culprits of the series of locked room murders. Are you denying that?”
“No, I'm not denying it. The culprits of The Glass House Murders are myself and Mr. Kagami. I told you before, Ms. Aoi's deduction was perfect.”
Seeing Tsukiyo puff out her chest with pride, Yuma continued “However.”
“There is something about The Glass House Murders far more important than the identity of the culprits.”
“Something more important than the culprits?”
Kuruma asked, brow furrowing even deeper.
“That's right. Mr. Kuruma, you've said it several times since arriving in the Tower. It's like you wandered into a mystery novel.”
“So?”
“So you're completely right. A bizarre glass spire built deep in the mountains, turned into a closed circle by an avalanche, a series of locked room murders, dying messages, codes written in blood, eccentric guests, a secret dungeon containing a skeleton, and even a secret passage. It's exactly like the world of a honkaku mystery novel.”
Yuma dramatically spread his arms.
“All mystery fans love serial murders in strange buildings. Ayatsuji Yukito's Bizarre House Murders series, Shimada Soji's Murder in the Crooked House, Higashino Keigo's The Pierrot of Cross Mansion, Nikaido Reito's The Terror of Werewolf Castle, Utano Shogo's The Long House Murders, Abiko Takemaru's The 8 Mansion Murders, Yonezawa Honobu's The Incite Mill... The list goes on. Especially if the building is in a closed circle, fans will eat it up.”
“Yuma, aren't you getting a bit off topic? It's like looking in a mirror.”
Tsukiyo let out an amused chuckle. Yuma said “Oh, excuse me.”
Being a great detective was more exciting than he'd expected. Or maybe he'd just picked up the habit from Tsukiyo.
“What is it you're trying to say, Dr. Ichijou? Please, get to the point.”
“I understand.”
Yuma nodded to Kuruma, licked his dry lips, and opened his mouth.
He uttered the truth.
“We are all characters in a novel. A honkaku mystery novel by the title of The Glass House Murders.”
“We're... characters in a novel?”
Kuruma muttered, tongue numb with confusion. Yuma nodded firmly.
“Yes. We didn't realize it, but for the past four days, we have been characters in a honkaku mystery novel, playing out our roles.”
“I-I don't understand...”
Kuruma shook his head, face warped by perplexion and fear.
“Are you insane!? Us, characters in a novel? There's no way something that absurd could happen!”
Yumeyomi screamed at him, but Yuma was unperturbed.
“No, that absurdity took place right here in this tower.”
“Stop it! You aren't making any sense!”
Yumeyomi ruffled her pink hair. Tsukiyo spoke for her.
“So that's what you're getting at, Yuma. This world is a stage for a metamystery, and we're the fictional characters acting on it.”
“Metamys... what? What's that?”
When Sakaizumi asked, Tsukiyo raised her index finger to the level of her face.
“It's a sub-genre of mystery. 'Meta' is a word referring to an elevated perspective or position. Metamystery is when that perspective is applied to a work of mystery fiction.”
Sakaizumi frowned, clearly not getting it.
“Put simply, it's a mystery in which the boundary between the fictional world and the 'higher level' of reality is blurred. Things like the author appearing as a character in their own work, the characters being aware that they're fictional, or the reader being the real culprit.”
“The reader is the culprit?”
Sakaizumi asked, confused, and Tsukiyo leaned forward and said
“That's right! The most famous examples are Tsuji Masaki's Working Title: The Middle School Murder Case and Fukami Reiichirou's The Last Trick. Tsuji Masaki also wrote 9 Challenges, where he achieved the remarkable feat of making everyone EXCEPT the reader into culprits. He's truly a rare master of tricks.”
“I understand what metamystery is. But what do you mean by us being characters? We're all real people.”
Sakaizumi ignored Tsukiyo's ramblings and addressed Yuma.
“Allow me to explain. To begin with, why did we all come to the Tower?”
“Why? Because Mr. Kozushima invited us.”
“That's right. And why did Mr. Kozushima invite us?”
“He said he had some big announcement to make... You said it was an unpublished mystery manuscript written before The Murders in the Rue Morgue.”
“Yes, that's what we believed at the time. That was the only way an unpublished manuscript could completely overturn the history of the mystery genre. However, that manuscript still has yet to be found. It isn't in the safe or anywhere in the secret passage. I snuck into the First room to check earlier, but it isn't in Mr. Kozushima's desk, either.”
“So where is it, then? Where is that precious manuscript?”
“I'll explain that in a moment, so please be patient. Now, let's move on to the story of the first incident.”
“You were the culprit of that incident. What is there left to say? Or are you trying to tell us you didn't do it after all?”
Yumeyomi cast him a scornful look.
“No, I won't say that. I gave Mr. Kozushima that capsule, then he clutched his throat and began to suffer. Everything after that was exactly as deduced. In The Glass House Murders, I am, undoubtedly, the culprit of Mr. Kozushima's murder.”
Yumeyomi started to speak, but only got out “Then-” before Yuma raised a hand.
“The problem is what happened after the first incident. Afterwards, everyone, including Mr. Oita and Ms. Tomoe, gathered together in the dining room to discuss our next move. Afterwards, we dispersed and returned to our rooms. At that time, as I was alone on the stairs, I was struck by the illusion that someone was following me. You said the same thing, didn't you Ms. Yumeyomi?”
When he asked her, Yumeyomi nodded hesitantly.
“Yes, I did feel it. As I was climbing the stairs, I felt the presence of something evil pursuing me.”
“As I said earlier, I believe that presence was someone moving on the hidden staircase on the other side of the wall. So, who was it on the staircase at that time?”
“Who?”
Yumeyomi looked around as if searching for a lifeline.
“At that time, we had all split off to go to our rooms at almost the same time. There shouldn't have been any time to go to the hidden staircase.”
“Then it must have been Mr. Oita or Ms. Tomoe. They were live-in servants who worked in the Tower, so they may have known about the hidden staircase.”
Sakyo posited the idea, but Yuma shook his head.
“Mr. Oita and Ms. Tomoe were cleaning the dining room at that time. Isn't that right, Sakaizumi?”
Sakaizumi lowered his head slightly.
“That's right. The three of us spent about fifteen minutes cleaning up together.”
“So then there is someone we don't know hiding in the Tower!”
Yumeyomi screamed, but Yuma casually dismissed her.
“That's unlikely. The hidden stairway is too narrow for a person to live in. In order to survive, the person would have had to regularly leave the hidden stairway. It would be extremely difficult for anyone to do that without being seen by someone at some point in the past four days.”
“But if it wasn't an invited guest, an employee, or an unknown third party, then there isn't anybody left.”
Kuruma grimaced as though he was in physical pain.
“That isn't true. There is exactly one person who could have used the hidden stairway at that time.”
“One person? Who is it?”
Yuma smiled and told them the name.
“Kozushima Tarou, the owner of the Tower.”
Everyone was silent. But it didn't look like they'd been shocked and rendered speechless. It was more like they were confused and not sure how to respond.
After ten or twelve seconds of silence, Kuruma spoke.
“I'm sorry, Dr. Ichijou, I don't think I heard you correctly. Could you repeat yourself?”
“No, you heard me right. Mr. Kozushima was the first person to use the hidden stairway.”
“Do you understand what you're saying? You poisoned Kozushima on the first night.”
“Yes, it's true that in The Glass House Murders, I poisoned Mr. Kozushima. But there's also no doubt it was Mr. Kozushima who used the hidden stairway after the first incident. I just proved it couldn't have been anyone else.”
“You've been incoherent for a while now. I can't believe you're sane.”
Kuruma stepped away from Yuma in fright.
“Ah, sorry. It's creepy when a man with a gun says and does incomprehensible things, isn't it? So, let me explain so you all can understand.”
Yuma gently cleared his throat.
“Mr. Kuruma, didn't you feel anything was off? When the avalanche blocked off the road and isolated the Tower right after the first incident.”
“No. I thought it was unfortunate, but mostly I was so distressed by the possibility that Kozushima had been poisoned that I couldn't think of anything else.”
“I was in the same boat. Although in my case, I was upset that you all had figured out that Mr. Kozushima had been poisoned. I'd been planning to let his death be ruled as a heart attack.”
Yuma smiled self-deprecatingly.
“There are many things about this Tower that seem odd. Would Mr. Oita and Ms. Tomoe really have participated in a crime as horrible as mass kidnapping and human torture just because their employer asked them to? If multiple human bodies had been left to rot until they were skeletonized, wouldn't the dungeon have been filled with the stench of decay? Is it really possible that a window would accidentally be designed such that it caused a fire inside the room every day? And would such a design flaw be left unattended in a Tower especially vulnerable to fire? Was there any need to go to the trouble of preparing unduplicable keys with IC chips for all the guest room doors? And is Mr. Kozushima being 'a bit of a hermit' really enough to explain why he built a bizarre tower out in the mountains, far from civilization, and lived there full time?”
Everyone listened to Yuma. Now they were properly shocked.
“When Mr. Kuruma said he felt like he'd entered a honkaku mystery novel, he'd inadvertently struck at the heart of the whole case. This Tower was intentionally created as the setting for a series of locked room murders within a closed circle.”
“It was created for locked room murders?” Sakyo asked, hand to his forehead.
“Yes, it was. A strange mansion is isolated from the outside world, and a series of unique murders taking advantage of the building's unique structure are committed. It's exactly the sort of thing that would happen in a classic honkaku murder mystery novel. But while 'classic' is all well and good, there is a fine line between classic and dated. It's such a well-worn concept that it has almost no originality left. And...”
Yuma looked at everyone on the far side of the sofa.
“A mystery novelist, a police detective, a psychic, a mystery editor, a cook, a butler, a maid, and... a great detective. It goes without saying that a unique cast like that would gather in a mansion. Yes... not only the Tower, but we were also prepared as part of a honkaku mystery novel.”
“What are you talking about!?”
A shriek echoed off the dining room walls.
“Enough already! We're characters in a novel, prepared for a murder case, I don't understand anything anymore!”
As Yumeyomi hunched over and clutched her head, Tsukiyo came over and gently stroked her back.
“She's right, Yuma. Being frustratingly indirect is one of the privileges of being a great detective, but if you go too far, it's just annoying. I think you should get to the point now.”
Having been advised by a senior great detective, Yuma nodded.
“I suppose you're right. Well then, let me get to the conclusion. We unconsciously became actors in The Glass House Murders, a honkaku mystery story penned by Mr. Kozushima.”
“Actors in a honkaku mystery story?”
Sakyo frowned.
“Yes. And The Glass House Murders was probably the unpublished manuscript that Mr. Kozushima was planning to present at this event.”
“Wait a minute. Wasn't the mystery Mr. Kozushima was to present written before The Murders in the Rue Morgue?”
“That was an assumption I made based on the information that it was an unpublished work that would completely overturn the history of the mystery genre. But I was wrong. I'm sorry I got your hopes up. Mr. Kozushima was planning to present a honkaku novel of his own creation.”
“A novel written by Mr. Kozushima...”
Sakyo's shoulders slumped.
“Mr. Kozushima was a serious mystery fanatic who aspired to be remembered as a mystery writer, not as a scientist. But he didn't have any talent as a storyteller. But he couldn't make himself give up, so he tried to compensate for his lack of talent with something he did have.”
“Something?”
“Financial resources. Cold, hard cash.”
“Money? You mean he was going to self-publish?”
In response to Sakyo's question, Yuma shook his head and said
“No. He created the world of his honkaku mystery novel in real life.”
“The world of a mystery novel, in real life...?”
Sakyo's head shook slightly, not understanding what he'd been told.
“Yes. The Glass Tower was designed and built specifically as the setting of a honkaku mystery novel, where three mysterious locked room murders would be committed. Of course, the window being a fire hazard was completely intentional.”
Yuma pointed to the glass window stretching out behind the group.
“Building a tower like this would cost a ridiculous amount of money!”
Appearing to have somewhat recovered from her panic, Yumeyomi's eyes, rimmed in pink eye shadow, were still wide.
“Yes, it probably cost several billion yen. But Mr. Kozushima was a multibillionaire, so that was no trouble. Five years ago, he nearly died of a heart attack. Ever since that day, his only purpose in life was to create a masterpiece that would leave his name etched in the history of the mystery genre.”
“Mr. Kuruma,” Yuma suddenly called. Kuruma, who had been standing slack-jawed, straightened up.
“You said it before, remember? Mr. Kozushima's mysteries lacked originality, and their logical developments were full of holes.”
“Oh, yes, I did say that.”
“If you think about it, the Glass Tower and the incidents that took place within clearly show that lack of originality and weak logic.”
“What do you mean?”
“Mr. Kozushima had a strong admiration for the Bizarre House Murders series, including The Decagon House Murders which sparked the shin honkaku movement, as well as its author, Ayatsuji Yukito. That feeling which bordered upon creator worship was a strong influence on him as an author, which led Mr. Kozushima to create a work that exactly followed the structure of The Bizarre House Murders, in which a series of murders takes place in bizarre mansions that become closed circles.”
“You mean it was a case of plagiarism?”
Sakaizumi spoke unsurely. It sounded like he wasn't quite following the conversation.
“I don't think I'd go that far. There isn't any building in the Bizarre House Murders series like the Glass Tower, and none of the tricks were directly copied, either. But the whole structure of the incident is too similar to write off as an homage. If I had to give it a name, it would be 'bad fanfiction'.”
“Bad...” Kuruma muttered.
“Yes, it's awful. I didn't notice before because I was too anxious about the ongoing case, but if you think about it calmly, The Glass House Murders is full of plotholes. How was Mr. Kozushima able to twist and then smash the model of the Glass Tower after taking tetrodotoxin, which works by paralyzing every muscle in the body? What was the point of creating the second locked room at all? And in the third case, if the culprit wanted the dungeon to be found, why did they leave the coded message 'KILL NAKAMURA SEIJI' instead of just writing the answer directly? And why didn't the fire alarm go off while the screen in the theater burned?”
Everyone gasped.
“He came up with an ingenious trick, so he used it without even coming up with a reason why. He wanted to create an atmosphere of tension, so he made the culprit do illogical things. They're common mistakes in mysteries with weak plots.”
“Wait,” said Kuruma. “You mean to say that this series of locked room murders that took place here in the Glass Tower was...”
Kuruma's tongue was tangled from his excitement, and he couldn't find the words. Yuma nodded and took over.
“Yes. They were all a work of fiction, written and directed by Kozushima Tarou.”
“A work of fiction...?”
Kuruma couldn't believe it.
“As much as he didn't like it, I believe your criticism was able to convince Mr. Kozushima that, no matter how much he wanted to, he would never be able to write a masterpiece that could ensure his name would be remembered forever. That's why he decided to instead try and create a work that only he could make. He would construct a building that looked like it could only exist in a honkaku mystery, fake a series of murders inside, and invite a group of guests to try and solve them. It's like an evolution of an escape room. A real honkaku mystery. If he published a novelization and released recorded footage of the incident, it would certainly capture the public's imagination.”
“So, when Kozushima died on the first night...”
“Right. He wasn't actually dead.”
Yuma spoke softly. Kuruma lowered his head as though his soul had left his body.
“But didn't we confirm Mr. Kozushima's death?” Sakyo asked uneasily.
“No, remember? Mr. Kagami was the only person to confirm it. Immediately afterwards, he refused to let anyone else touch Mr. Kozushima's body, kicked us all out of the room, and banned us from ever returning. It was the same with the second and third incidents. Mr. Kagami was the only one who confirmed the victims were actually dead, and he refused to let anyone else examine the bodies.”
“So then Mr. Kagami is...”
“Yes, he was in on it. Considering how good his acting was, he was probably hired by Mr. Kozushima from a theatrical troupe. At the very least, I doubt he was a real police detective. Mr. Oita and Ms. Tomoe also knew from the beginning that the whole mystery was an act, and cooperated with Mr. Kozushima's plan. The roles of the victims and culprit were decided upon from the beginning.”
Yuma raised the corner of his lips.
“The real truth behind the second and third incidents is that the victims fabricated them themselves. Mr. Oita locked the door from the inside, wrote 'SPIRITED AWAY FROM CHOGATAKE' in animal blood or something else they'd prepared in advance, and directly started the fire with a lighter. Ms. Tomoe brought the wedding dress to the Sixth room, changed into it, created fake slashes on her thighs with makeup, and lay down on the bed.”
“Then... You too, Dr. Ichijou? You were the one to poison Mr. Kozushima. Then that also wasn't real...? But...”
Sakyo's eyes wandered as if struggling to keep up with his own thoughts.
“No, I had every intention of poisoning Mr. Kozushima. But now I realize that was part of his plan. I heard that the position of Mr. Kozushima's personal physician was open from an acquaintance. Mr. Kozushima must have known that the lawsuit he'd filed would prevent my sister, who suffered from an incurable disease, from receiving the treatment she needed. He hired a private investigator to find a doctor who had a good reason to kill him, then indirectly informed me that he was vulnerable.”
Yuma clenched his fist, enraged that his feelings for his sister had been exploited for this sick game.
“Then, he told me a non-toxic powder was pufferfish liver, and had Mr. Oita, who was always present during my checkups, treat me as an ordinary guest for that day only. He'd calculated that I wouldn't pass up that once-in-a-lifetime opportunity.”
“But even so, he couldn't have been sure you would have actually poisoned him.”
“If I hadn't, Mr. Kagami would have played the role of the culprit in that case as well. But just as Mr. Kozushima planned, I did try to poison him. He must have been so happy. He got to watch me being torn apart by guilt, then stumble around in confusion when two more murders took place without my involvement.”
“Watch!?” Sakaizumi shouted. “You mean Mr. Kozushima is alive and has been watching us?”
“Yes, he has. After the first incident, the First room was declared off limits. He'd been observing us ever since. I believe he used the one-way mirrors in the guest rooms, and set up hidden cameras in the game room, dining room, and underground storeroom sending live footage to the computer in his room. He sat and watched us, running around like chickens with our heads cut off and dancing to the tune of the story he'd written. He must have felt like God.”
Yuma clicked his tongue. After a moment, Kuruma took a deep breath.
“Dr. Ichijou, I don't know what to say. Your story is so far beyond belief that I struggle to accept it. But at the same time, it seems very logical. Do you have any evidence to support your theory?”
“Yes, several pieces. First, there's the circumstantial evidence.”
“Circumstantial evidence?”
Kuruma wrinkled the base of his nose.
“Remember how Ms. Tomoe looked at dinner on the second day. She must have realized the culprit's motive by then. That being the case, it was only natural she'd realize she was going to be the next target.”
“Yes, that's why she looked so frightened after the second incident.”
“At a glance, she did appear scared. But if that was the case, isn't it odd that she ate dinner first?”
“What do you mean?”
“She ate from the buffet without a hint of caution. If she really believed her life was in danger, wouldn't she have been afraid of poison? Mr. Kozushima was poisoned, and the highly poisonous powdered pufferfish liver was still in the Tower.”
“Now that you mention it...”
Kuruma turned to check the expressions of the rest of the group.
“Well, you could argue she was panicking and not thinking clearly. But there's more circumstantial evidence. The snow.”
“Do you mean footprints?”
“No. You remember it snowed a bit on the first night? As a result, when we went to the parking lot after the second incident and saw our tires were flat, there was a bit of snow on the glass of the display room. The heating in that room is broken, as we were told. But if that's the case, isn't it strange that there wasn't snow on the glass of the First room as well? Remember? The heating in that room was supposed to have been turned off to slow the decay of Mr. Kozushima's body.”
“But if there wasn't any snow on the First room, that means...”
“Right, after the incident, the heating in that room was turned back on. Why? It's simple: because Mr. Kozushima was still alive.”
“I see. That's certainly convincing, but it isn't conclusive. Earlier, you spoke as if you had more direct evidence. Would you please tell us what it is?”
Kuruma looked to him. Yuma nodded.
“Rigor mortis. The progression of Mr. Kozushima's rigor mortis is the strongest evidence that The Glass House Murders was a work of fiction.”
“It's true that Mr. Kozushima's body had signs of rigor mortis when we checked it yesterday, but how is that evidence?”
“Last night, Mr. Kozushima's arms and shoulders showed only weak signs of rigor mortis. At the time, I assumed that was because the stiffness was fading. Rigor mortis reaches its peak between twelve and twenty four hours after death, then slowly loosens. But I was wrong.”
“Wrong? What were you wrong about?”
“Just before I called you all here, I lifted Mr. Kozushima's wrist, and his entire body moved. The muscles of his arms and shoulders were stiff as logs.”
“What are you saying? You just said that rigor mortis weakens over time, didn't you?” asked Yumeyomi.
“That comes after the stiffness has peaked. In other words, what I felt yesterday was Mr. Kozushima's rigor mortis just beginning to set in. Which means...”
“Kozushima wasn't killed three days ago. He was killed yesterday...”
Kuruma finished the thought for him.
Yuma replied “That's right.”
Was that enough? Would they be convinced? As he waited to see everyone's reactions, Tsukiyo raised her hand.
“May I say something, Yuma? There's still one thing you haven't explained. Mr. Kagami. After he confessed to the crime, he died after swallowing the contents of the pill case you slipped into his pocket. If the capsule you gave Mr. Kozushima didn't actually contain any poison, he shouldn't have died. Or was that all an act, and Mr. Kagami, who collapsed in the dining room, is actually still alive?”
“No, he's dead. And not just Mr. Kagami. Mr. Kozushima, Mr. Oita, and Ms. Tomoe were all dead when I checked their bodies yesterday evening.”
Sakaizumi groaned, his hope that Madoka might still be alive dashed.
“Yes, when you, I, and Mr. Kuruma investigated last night, all three victims, including Mr. Kozushima, were completely dead.”
“Then isn't that proof your entire hypothesis so far isn't true?”
“No, not quite.”
Yuma gently shook his head.
“Without a doubt, The Glass House Murders, the series of locked room murders that occurred in this tower, were a work of fiction masterminded by Mr. Kozushima. But there was a major miscalculation in his plan.”
“A major miscalculation? What on Earth was it?”
Kuruma asked nervously.
“There was a monster in the Tower.”
“A monster!?” Yumeyomi's voice broke. “You mean there was a monster we don't know about hiding in the Tower?”
“No, that's not it. The monster is one of us. Mr. Kozushima carelessly unleashed a terrible disaster upon his home. That monster escaped from his control and took over The Glass House Murders.”
“What do you mean, took over?”
Sakyo shrank within himself as though to protect himself from cold.
“Someone actually killed Mr. Kozushima and the other three victims, turning the fictional murder case into reality.”
Everyone's faces stiffened as Yuma continued his explanation.
“The knife in Mr. Kozushima's chest wasn't posthumous mutilation for the sake of revenge. It was Mr. Kozushima's real cause of death. They stabbed him while he was still alive.”
“But Kagami's death at the end... According to your previous hypothesis, what he took shouldn't have been poison...” Kuruma gasped.
“The monster predicted that I would force the pill case on Mr. Kagami to frame him, and that he, as an actor, would do the most dramatic thing and swallow the capsules inside. That's why they swapped out the contents of my pill case for real poison.”
“Real poison? There's no way they'd conveniently have something like that on them.”
Sakaizumi spoke in a high-pitched voice, as though he was desperately trying to cast off the terrifying hypothesis.
“They obtained it within the Tower, Sakaizumi. There was a deadly poison in the underground storehouse. Rat poison.”
Sakaizumi's eyes went wide.
“Ms. Tomoe said she put rat poison in the underground storeroom to get rid of mice in winter. The monster swapped the contents of the capsules in the pill case with rat poison.”
Yuma scratched his temple.
“Thinking with a clear mind, Mr. Kagami clutched his chest, vomited, and then collapsed. None of those are symptoms of tetrodotoxin, the poison contained in pufferfish. He was probably poisoned with zinc phosphide: rat poison. Zinc phosphide reacts with stomach acid to form a poisonous gas called phosphine, which attacks the central nervous system and halts breathing.”
As Yuma caught his own breath, surprisingly exhausted, Tsukiyo narrowed her eyes and took a step forward.
“That's an interesting story, Yuma. Now, let's get to the highlight of any good mystery. Who exactly is the 'monster' you're accusing?”
Yuma and Tsukiyo's eyes met. Their gazes merged. Yuma smiled and quietly told them.
The true identity of the monster lurking in the Glass Tower.
“It's you, Ms. Aoi. You are the monster who killed Mr. Kozushima and the others and took over The Glass House Murders.”
A few moments of silence passed, then everyone around Tsukiyo stepped back, fear across their expressions. But Tsukiyo herself didn't lose the gentle smile from her handsome face.
“So I'm the one who killed the three of them – well, four if you count Mr. Kagami. That's quite an interesting theory, Yuma.”
“Looking back, you were constantly giving me clues. You were the one who was most insistent that we'd walked into a honkaku mystery novel, and you were the one to dub the case The Glass House Murders like it was a work of fiction. When you took over Mr. Kozushima's story on the third day, you realized that he was directing a title called The Glass House Murders. Ah, thinking on it, that was a major clue that we didn't need to take into account the Late Queen Problems when discussing The Glass House Murders.”
“Oh? How is that a hint that the Late Queen Problems weren't needed?”
Tsukiyo asked with genuine interest.
“One solution to the Late Queen Problems is to have a higher being – that is, one with meta-level awareness – intervene and guarantee the veracity of the evidence in question. In The Glass House Murders, you killed Mr. Kozushima, the meta-level being known as the author, and usurped his position, thus granting yourself the power of a meta-level great detective. It's the same as Maya Yutaka's God Game, which solved the Late Queen Problems by giving the detective role to a higher being called God.”
“I see, what an interesting idea. As expected of a mystery buff of Yuma's caliber. But...”
Tsukiyo's eyes narrowed.
“Isn't it a bit far-fetched to treat me as the culprit for a reason like that? Do you have any actual evidence tying me to the crimes?”
“Of course.”
When Yuma nodded, Tsukiyo cheerfully said
“Ooooh! Do tell.”
“The first question is when was Mr. Kozushima's The Glass House Murders taken from him? In other words, when did the culprit actually kill him and the other victims?”
Tsukiyo raised her palm and beckoned for him to continue.
“At the very least, everything was still going according to plan yesterday morning, when Ms. Tomoe was found in the locked Sixth room in a wedding dress. At that moment, Mr. Kagami prevented anyone from getting close to Ms. Tomoe. He was the one who told us she was dead and that there were torture marks on her thighs. He kept us from getting close so we wouldn't realize that she was still alive and the wounds on her thighs were faked with make up. Then, after reading the bloody writing on her corset, we went to the dungeon and found the fake skeletons. That much was probably all part of the scenario Mr. Kozushima had planned.”
“Wait, the skeletons were fake?”
Yumeyomi blinked. Yuma grimaced to have his story interrupted.
“The bodies of the 'kidnapping victims' probably weren't rotted. They were left in a dark dungeon so we wouldn't notice that, and locked in cells so we couldn't observe them up close. It's entirely possible they were real human bones. It's possible to purchase skeletal specimens overseas, after all. Mr. Kozushima would have wanted his masterpiece to be that realistic.”
Yuma turned back to Tsukiyo, who was still standing calmly.
“So, yesterday morning, The Glass House Murders was still proceeding smoothly. But by that evening, Mr. Kozushima, Mr. Oita, and Ms. Tomoe were actually dead. Somewhere between those two times, the serial murder case that was supposed to have been fictional became real. What bothers me is the incident where I was pushed down the stairs. At that time, you shouted that someone was eavesdropping outside my room, so we both went out to look for them. I went up the stairs to the display room, and when I descended back down to the Fourth room, someone pushed me from behind.”
“But there was no one in the display room or on the stairs.” Tsukiyo raised her pointer finger. “In that case, couldn't it have been Mr. Kagami? Mr. Kagami, who was in the Second room, could have snuck out of the room after you passed his door and pushed you from behind.”
“Until now, I'd believed the same thing. But within the context of the fictional The Glass House Murders, that's odd. I was lucky and managed to escape serious injury, but a fall down steep stairs like the ones in the Tower could easily kill someone. There's no way Mr. Kagami, who was just an actor playing a role, would have done that.”
“Well then, Yuma, where do you think the person who pushed you came from?”
“The Third room. Someone hiding in the Third room pushed me down.”
“What!?” Sakaizumi shouted. “W-What are you talking about? I would never do something like that! Why would I even want to hurt Dr. Ichijou!?”
“Calm down,” Yuma told the hysterical Sakaizumi.
“I don't think you did it, Sakaizumi. At that time, you, Mr. Kuruma, and Mr. Sakyo were in the game room together.”
Sakaizumi sighed in relief as Tsukiyo shrugged.
“So how did the person who pushed you get into the Third room? Mr. Sakaizumi, are you in the habit of leaving your door unlocked when you leave the room?”
“No, I lock it properly. I've been terrified these past four days, so I definitely locked it properly at that time.”
“In that case, it's impossible for anyone other than Mr. Sakaizumi to have entered or left the Third room through the door. Do you think they entered via the hidden stairway?”
“No. Mr. Kozushima was still alive at that point, organizing The Glass House Murders. If someone had used the hidden stairway, he or one of his accomplices would have noticed.”
“Then no one could have entered the Third room.”
“That isn't true. There is one person who could have opened the door. You, Ms. Aoi.”
“Me?” Tsukiyo pointed to herself. “You think I used my lockpicking skills to unlock the Third room? That isn't true. The keys to the Tower are made with special IC chips. It's impossible to open the door to the Third room without the Third key or the master key.”
“Yes, which is why you used the Third key.”
The mocking smile on Tsukiyo's face finally faded.
“You told me yourself. As a great detective, you have the skills of a pickpocket. And on the third day, after the third incident, when we were putting the master key in the underground safe, you supported Sakaizumi when he staggered due to the shock of losing Ms. Tomoe. That's when you stole Sakaizumi's key from his pocket.”
Sakaizumi looked at Tsukiyo in shock.
“You had the key to the Third room in your pocket when you raised that fuss about someone eavesdropping, sending me to the display room. Then, you quietly hid in the Third room. When I passed by on the way down, you left the room and pushed me from behind.”
“B-But Dr. Ichijou, I have the key with me,” Sakaizumi said, taking it from his pants pocket.
“She returned it to you when we went to the game room to persuade Mr. Kuruma to help us retrieve the master key and she shook you while you were passed out drunk. Isn't that right, Ms. Aoi?”
When he turned the conversation back over to her, the corners of her thin lips turned up.
“How sad. You suspect me of trying to kill you, my precious partner.”
“You weren't trying to kill me. You just wanted to incapacitate me for a certain period of time. I was injured and brought back to the Fourth room, and after I drank the water you offered me, I slept like a log. Thinking back, even if I was suffering from sleep deprivation due to stress, it's abnormal to fall asleep for half a day. There must have been drugs mixed in the water you gave me. You told me you keep a large amount of drugs on you in case of emergency. If it was mixed into water and put the person who drank it to sleep without them suspecting anything, it was probably risperidone. It's odorless and tasteless.”
“Why would I have put you to sleep?”
“That's easy.”
Yuma stared directly up into Tsukiyo's eyes.
“It was so you could go murder Mr. Kozushima and the others and take over The Glass House Murders.”
As Yuma glared at Tsukiyo, smile still plastered on her face, he began to explain.
“You probably went down to the underground storeroom as soon as you'd confirmed I was asleep. There were good odds Ms. Tomoe would go gather food to deliver to Mr. Kozushima. When she arrived, you threatened her with a knife to force her to follow you back to the Sixth room... where you tortured her.”
Sakaizumi glared at Tsukiyo with wide, wild eyes. But Tsukiyo's expression didn't budge an inch.
“She told you all about The Glass House Murders, the passcode to the hidden stairway, and their plans for the future. I'm sure that included the information that Mr. Kozushima and the other victims weren't to have any contact with Mr. Kagami once the game had started. If you hadn't been able to confirm that, there would have been a chance that Mr. Kagami would realize that Mr. Kozushima and the others really had been murdered.”
Yuma smiled wryly.
“The meta-level entity controlling the incident avoids any contact with his characters. I suppose that's only natural for Mr. Kozushima, who was abnormally particular about these sorts of things.”
“...And then what happened?”
Sakaizumi's voice had lowered dangerously. His eyes never once moved from Tsukiyo as she stood next to him.
“After she told her everything she knew, Ms. Tomoe was murdered in the exact same way as her character in The Glass House Murders: changed into a wedding dress and left on the bed.”
Yuma heard Sakaizumi's teeth grinding as he turned back to Tsukiyo.
“Afterwards, you killed Mr. Oita and Mr. Kozushima. There was no way you could force Mr. Kozushima to swallow poison, so you had no choice but to stab him to death. Then, after you finished committing all the crimes, you changed clothes, returned to my room, and took a shower to wash off all the blood.”
Having explained the outline of the case, Yuma closed his mouth and waited for Tsukiyo's response. She suddenly started clapping.
“That's great, Yuma. A wonderfully logical theory. But I think the foundation is a bit weak.”
“Foundation?” Yuma replied.
“Yes, your theory is built upon the assumption that I stole Mr. Sakaizumi's key. But there's no evidence I did that. Do you have any solid evidence of my hijacking The Glass House Murders?”
“Yes, I do.”
Yuma's bold answer didn't appear to shake Tsukiyo much.
“Oh? Then please, share with the class.”
“It's the capsules in the pill case. Those capsules which were supposed to have contained fake poison were somehow swapped for ones containing rat poison. I hid that pill case in the tank of the toilet on the first night and didn't remove it until last night, when I put it in my jacket pocket. In other words, after you returned from killing Mr. Kozushima and the others, you swapped them when you entered my bathroom to take a shower.”
“It's possible they were swapped before then.”
Tsukiyo sounded like she was taunting him.
“No it isn't. I always locked my door whenever I left the room.”
“Maybe they entered via the hidden stairway.”
“The real culprit wasn't able to use the hidden stairway until after they killed Mr. Kozushima and the others on the afternoon of the third day.”
“So someone other than myself entered the Fourth room via the hidden stairway between the time the murders were committed and when you woke up.”
“That isn't possible. You know that, Ms. Aoi.”
Yuma felt the corners of his mouth turn upwards.
“You were supposed to have been taking care of me while I slept. If someone had come from the hidden stairway, you definitely would have seen them. But you didn't say anything about that. That's the proof you're the real culprit who killed Mr. Kozushima and the others and swapped the contents of my pill case for capsules of rat poison.”
Tsukiyo smiled with delight and clapped again.
“Excellent, truly excellent, Yuma. Your deduction is perfect. Completely perfect, except for one flaw.”
“A flaw? What's wrong with it?”
“There's nothing strange with your deductions; they're all perfectly sensible. But it's all based on the premise that Mr. Kozushima spent quite a lot of money to orchestrate a fictional story called The Glass House Murders.”
“But the hidden stairway was used by the culprit.”
When Yumeyomi interrupted her, Tsukiyo gave her a sharp glare that made her shriek and back away.
“The hidden stairway doesn't prove anything. Maybe Mr. Kozushima was just a voyeur. The only other evidence we have is subjective claims of people's 'perceptions'.”
Yumeyomi shrank back, unwilling to argue with Tsukiyo any further.
“The fact that Ms. Tomoe didn't hesitate to eat dinner on the second day, the lack of snow on the window of the First room... none of that is proof that the three locked room murders were fiction. And it's hard to call Mr. Kozushima's rigor mortis 'evidence' when you're the only one who's confirmed it. If you want to accuse me, a great detective, of murder, you need solid evidence, not vague claims. Do you have it, Yuma?”
“...No, I don't have it yet.”
“So what you've said is nothing more than a load of nonsense, a final desperate attempt by a murderer to explain away his crimes.”
Tsukiyo looked down and shook her head, sighing.
“That's unfortunate.”
“Don't jump to conclusions. I said I don't have it yet.”
“What do you mean?”
Tsukiyo's head came back up. Her voice sounded hopeful.
“Mr. Kuruma, do you still have the bottle of poison you took from the display room?”
Kuruma, who'd suddenly been questioned, went “Ah, um...” and took the small glass bottle labeled “Pufferfish Liver” out of his pocket.
“Please throw it to me.”
“This bottle? Why?”
“I need it. Please.”
Yuma asked politely, and after a slight hesitation, Kuruma threw the bottle in an underhand toss. The bottle flew in a parabola directly into Yuma's hand, whereupon he used his thumb to pop open the lid. Kuruma realized what Yuma was about to do, and he gasped.
“Stop, Dr. Ichijou! Don't do anything stupid!”
“It isn't stupid. Mr. Kozushima, Mr. Oita, and Ms. Tomoe all said this bottle contained deadly poison. If that was a lie, it would be proof this is just a prop to force me to play the role of a murderer in The Glass House Murders, the fictional story written by Mr. Kozushima.”
But if he was wrong, swallowing it would cost him his life. The bottle shook in Yuma's hand.
He was literally risking his life for the truth. He wondered if he could actually do something like that.
All the moisture had been drained from his mouth. He began to laugh, his knees shaking. He lost all sense of perspective. His mind was filled with images of the bottle leaping from his hand and attacking him. He couldn't move, as though his body was bound in steel chains.
He couldn't breathe. It felt like the oxygen in the room was thinning. Yuma raised his head and met Tsukiyo's eyes. She wore a smile as carefree as a young girl's.
The moment he saw that face, his paralysis was released. Yuma put the bottle to his mouth and poured every last grain down his throat. As everyone in the room screamed, Yuma opened his eyes wide and his whole body shook. A hiccup escaped from his throat.
“Spit it out! Spit out that poison right now!”
As soon as he heard Kuruma cry out, his emotions overflowed.
“A... Aha... Ahahahahahaha!
Laughter erupted from the depths of his soul. He coughed and choked several times, but he couldn't help it. He just couldn't stop laughing.
After several dozens of seconds, Yuma finally regained his composure and turned back to Kuruma and the others, who all stood with stunned expressions on their faces.
“A-Are you alright?”
Kuruma asked nervously, as if he still doubted his sanity. Yuma held the bottle up high.
“It's sugar!”
“What?”
“It was sugar. The bottle contained nothing but sugar.”
Yuma stuck a finger in his mouth and licked the white powder from his fingertip.
“Man, that is sweet. Makes me want coffee.”
Yuma stuck his tongue out at Tsukiyo.
“How about that? I think I make a pretty good detective.”
“You're a great detective, Yuma.”
With nothing but earnest joy from the bottom of her heart, Tsukiyo proudly puffed out her chest and, prefacing her announcement with a “Well then,” said:
“Allow me to introduce myself once more. I am the monster who has infiltrated this Glass Tower. I am Aoi Tsukiyo, the great detective of The Glass House Murders and the true culprit of the tragedy that occurred in the Glass Tower.”
“You... You're the real culprit...”
Kuruma's face twisted with fear.
“Yes, that's right, Mr. Kuruma. I am the one who killed Mr. Kozushima, Mr. Oita, and Ms. Tomoe and took over The Glass House Murders. Ah, I also switched the capsules with rat poison, which indirectly makes me Mr. Kagami's killer, as well.”
The moment Tsukiyo replied, as casual as when she talked about the weather, a bestial roar rang out.
“How could you!? How could you kill Madoka!?”
Sakaizumi, face red with rage, attacked Tsukiyo. However, Tsukiyo dodged with a dancer's grace and pulled a black object from the inside pocket of her suit, which she placed to Sakaizumi's neck. Sakaizumi convulsed as though he'd been struck by lightning, then fell face first to the floor.
Looking down at Sakaizumi, who had landed with an alarming thud, Tsukiyo raised the object in her hand.
“It's a stun gun. Being a great detective means you often get into dangerous situations, so I always carry one with me. It's quite useful for self defense. And...”
Tsukiyo paused long enough to flash a bewitching smile.
“It's also useful for stopping people from resisting so you can kill them any way you want.”
Sakaizumi's body was motionless, but he must have still been conscious, as he let out a wheeze. Tsukiyo put her knee on his neck and put her weight on it, saying “Please be quiet for a moment.” Sakaizumi made a noise like a crushed frog.
“Get away from him.”
Yuma aimed the muzzle of the shotgun at Tsukiyo.
“Now, now, Yuma, let's not get violent. That's a shotgun you have there. If you pull the trigger, it will release a blast of pellets over a wide area. It won't only be me you hit. Mr. Sakaizumi and possibly even Mr. Kuruma would be killed as well.”
Tsukiyo let out a mocking chuckle. Yuma bit his lip and lowered the gun.
“I'm glad you understand. I can't speak calmly with a gun pointed at me.”
“You! Aren't you supposed to be a detective!?”
Yumeyomi pointed a trembling finger at Tsukiyo.
“I'm not a detective, I'm a great detective. I was a great detective.”
Tsukiyo glared at Yumeyomi, who let out a faint scream before fainting. Kuruma stepped forward as if protecting her.
“Ms. Aoi, why did you, a great detective, do this?”
Tsukiyo put a hand to her chin and hummed in thought.
“So, the motive... Personally, I prefer whodunits and howdunits to whydunits, but what about it? Why don't you all try to deduce my motive for killing Mr. Kozushima and the other? Mr. Kuruma?”
“...Did you have some sort of grudge against Kozushima? So you hijacked his plan to commit the perfect crime.”
“That's not it, Mr. Kuruma. It was nothing so simple as a crime born of hatred. My crimes were committed with much nobler intentions.”
Tsukiyo turned her head back to Yuma and narrowed her eyes provocatively.
“Do you understand, Yuma? What I was thinking when I killed Mr. Kozushima and the others?”
“Yes... I understand.”
Yuma said, his voice low.
“You didn't like The Glass House Murders.”
A smile spread across Tsukiyo's face like a blooming flower.
“She didn't like it... What are you saying...?”
Perhaps sensing some evil presence, Kuruma's voice was weak. Yuma took a deep breath.
“I mean exactly what I said. As I explained earlier, the plot of The Glass House Murders as written by Mr. Kozushima was full of holes. As someone who loves mysteries to the point of obsession, Ms. Aoi couldn't forgive that. Am I right?”
When Yuma offered her a chance to explain herself, Tsukiyo pointed her chin back at him, encouraging him to continue.
“On the morning of the second day, you noticed something was off with the window of the First room, and when Ms. Tomoe ate dinner without showing any fear of poison, you realized that everything happening in the Tower was a work of fiction. Come to think of it, you were the first person to encourage Ms. Tomoe to eat. That must have been how you confirmed it.”
“No, that isn't correct. I noticed something was off much earlier. The first time I heard that the Tower was an exact replica of a TRIDENT.”
“...I see. After the first incident, when we went to the display room, you ran around like a little kid. You weren't excited to see the Kozushima Collection, you were listening to the sound of your footsteps to find the hidden stairway.”
By that point, she had already realized that the spiral staircase should have formed a double helix... Come to think of it, when he visited the Fifth room on the second day, Tsukiyo's suitcase was directly over the mirror, and all of the books on the bookshelf had been removed. It was to prevent anyone from peeping or entering through the hidden stairway. Yuma felt a chill down his spine at Aoi's overwhelming intelligence.
“You have a good memory, Yuma. That's true. But, well, I was also excited to see the Kozushima Collection.”
Sakyo pointed at Tsukiyo, who sounded amused with the whole thing.
“So when you realized you'd been tricked by Mr. Kozushima and his servants, it made you angry?”
“No.” Yuma shook his head. “Ms. Aoi loves mysteries from the bottom of her heart, so even if it's fiction, she would never be angry about being allowed to enter the world of honkaku mystery like this. On the contrary, she must have been thrilled, eagerly anticipating what sort of incident would come next. In fact, she was extremely excited non-stop until the second day. The problems began with the locked room murder on the third day.”
“What was wrong with the third day's incident?”
“The trick was bad. The body slid along the slope of the Tower and landed perfectly in bed. It just didn't work. A body dropped down four stories would be likely to break a window, or maybe its momentum would send it flying over the open window entirely. It was hard to imagine that a real culprit would ever execute such a sloppy trick. And the solution also lacked originality. There are already extremely famous works of Japanese mystery with solutions involving sloped buildings.”
Yuma turned to Tsukiyo, thinking of a certain book, and Tsukiyo silently nodded. Yuma continued.
“On the second day, there was still the question of why the culprit needed to lock the door, but the trick itself was brilliant. It took advantage of the unique architectural characteristics of the Glass Tower, and even had the unique idea of darkening the tablecloth with blood so it would ignite. It must have been the greatest trick Mr. Kozushima ever came up with. You were satisfied with it, Ms. Aoi. That's why you were still excited on the second day.”
Tsukiyo didn't reply in words. But the amused look on her face clearly communicated that Yuma's idea was correct.
“I'm sure it was after coming up with that trick that Mr. Kozushima spent the money building this Glass Tower and started planning a real honkaku mystery incident. But he just wasn't talented enough to maintain the quality of the tricks and the details of the crime for the other cases. When you saw the third crime scene, you realized that The Glass House Murders would be a complete failure. And furthermore, when you saw the cheesy production of the dungeon set, you were so disappointed you fell into depression.”
He remembered Tsukiyo's sorrowful profile on the third day. He'd thought she was disappointed with herself for being unable to prevent a new victim from being killed, but in actuality, she had been wallowing in dark, swirling thoughts and concocting a terrible plan.
“That was why you decided to take over Mr. Kozushima's plan. While playing the role of detective in The Glass House Murders, you also played the role of the real world culprit who killed Mr. Kozushima and the others, making the three locked room murders real. You became a meta presence in place of Mr. Kozushima, overwriting the poor work that was The Glass House Murders and turning it into an extraordinary double-layered tragedy, an artistic, beautiful work of honkaku mystery.”
Words of praise naturally spilled from Yuma's mouth. The crimes that Tsukiyo had committed were inhuman and beyond forgiveness. But the mystery that had been born of her little grey cells was so meticulously calculated that a mystery maniac like him couldn't help but be moved.
“Thank you, Yuma. I'm truly grateful.”
Tsukiyo bowed respectfully.
“I never could have asked for someone who would understand my feelings to this extent. Yes, I was disappointed. A huge glass spire with a double spiral staircase running through is center, full of locks fitting keys that could never be duplicated, and a unique array of guests invited. Mr. Kozushima was the only one in the world who could have prepared such a perfect setting for a honkaku mystery. This Glass Tower is a miracle, born of his enormous wealth and bottomless love for mysteries. But unfortunately, he lacked the ability to construct a worthy puzzle. Apart from the second case, The Glass House Murders is a thoroughly mediocre mystery. No matter how high quality the ingredients used, an unskilled cook can never produce anything but garbage. So I took over from Mr. Kozushima, cooked in his place, and treated everyone to the finest meal.”
Tsukiyo turned to Kuruma and amiably asked “So? How did it taste?”, tilting her head to one side. Kuruma's cheeks twitched.
“You mean you killed four people just because you were disappointed by Mr. Kozushima's writing?”
“No. If it was just a bad story, I probably would have stuck to my role as the great detective of The Glass House Murders to the end. What drove me was disappointment, and... anger.”
“Anger? What did you have to be angry about?”
“Mr. Kozushima seemed to be a fair man when it came to mysteries. Not only did he give us clues to solve the three locked room murders, but he also gave us clues that all of the incidents that took place in the Tower were fictional. By telling us that the Glass Tower was an exact replica of a TRIDENT, he hinted at the existence of the hidden stairway, and when he told Yuma he would 'publish an unprecedented manuscript that would completely overturn the history of mysteries', that was also a hint. Oh, and the fact that the heating in the display room is broken is also a lie. By setting things up like that, he created a situation where snow would gather on the glass of the display room, but not the First room, creating a clue to his survival. And Mr. Kozushima placed the biggest hint in everyone's rooms.”
“The biggest hint? What?”
Without answering Kuruma's question, Tsukiyo turned back to Yuma.
“Yuma, you said that when I killed Mr. Kozushima and the others on the third day, I found out the title of the honkaku mystery novel I'd been placed in was The Glass House Murders. But that's wrong. I've known the title for a long time now. I first mentioned it on the evening of the third day because I figured that, now that I had taken Mr. Kozushima's place as the story's meta-being, it would be unfair of me not to acknowledge it.”
“How did you know it that early?”
Yuma frowned. Tsukiyo gave a small scoff.
“Hmm, Yuma, you're a bit of a scatterbrain for a great detective. The clue was right in front of you all along. On the top shelf of each room's bookshelves, number one through ten.”
“The top shelf...”
Yuma remembered the bookshelf in the Fourth room. The upper shelves should have been lined with works by Shimada Soji, Ayatsuki Yukito, Norizuki Rintaro, Arisugawa Alice, and other names you'd have expected from a lover of shin honkaku stories like Kozushima. The top shelf in particular had eleven books from The Bizarre House Murders, from The Decagon House Murders to The Strange Masks House Murders...
When his thoughts reached that point, Yuma screamed “Aah!?”
“It seems you've noticed. The Bizarre House Murders series is only ten books long. But for some reason, there are eleven volumes of the series on the bookshelves in each room. Why? The answer is simple. This was added.”
Tsukiyo took a book from her suit pocket. The book, which was designed in an exact replica of one of Kodansha's publications, was entitled The Glass House Murders, and had the author's name “Kozushima Tarou” written on its spine.
“Look inside.”
Tsukiyo casually tossed the book to Yuma. Yuma carefully picked up the book from his feet and flipped through the pages. The publishing information was blank, but on the first page was a 3D diagram of the Glass Tower and a list of characters.
Yuma bit his lip when he saw his own name on the list.
“I couldn't forgive this. The Bizarre House Murders was the spark that started the entire shin honkaku movement. You could call it a symbol of the genre. Naming a work too poor to even be called an homage after it and trying to add it to the real series is an unforgivable act. It's nothing but an insult to the entire genre of honkaku. Don't you agree, Yuma?”
––I want to be Ayatsuji Yukito.
Yuma remembered what Kozushima had said to him on the first day. At the time, he'd thought the words were a sign of his great respect for Ayatsuji, but in reality, Kozushima may have been filled with envy.
If he'd focused on being a mystery novelist like he wanted instead of a researcher, he could have been the spark that started the shin honkaku movement, not Ayatsuji Yukito.
That envy had consumed him and become an obsession materialized in the form of the Glass Tower. Kozushima had tried to cover up his inferiority complex by creating a honkaku mystery in real life and adding it to the Bizarre House Murders series as The Glass House Murders.
But that act had drawn the wrath of Aoi Tsukiyo.
“...But that doesn't mean you can commit murder over something like that.”
“No, I can. People kill when the things they love most in the world are trampled upon. For you, it was your sister. For me, it was the mystery genre. That is the only difference between you and me.”
Tsukiyo spoke forcefully and with zero hesitation. At that moment, Kuruma spoke up.
“No, Ms. Aoi, your actions are completely unreasonable.”
“Unreasonable? Me? How could that be?”
All of the warmth had vanished from Tsukiyo's voice.
“You have such a strong desire to be a great detective. You told us you'd wanted to be a great detective since you were a child. And yet, it's impossible to be a great detective after killing four people. Now you'll never be able to work as a great detective again.”
When she received Kuruma's rebuke, Tsukiyo put her hand over her mouth and looked down. Soon, her shoulders began to tremble. Unable to contain herself, a chuckle began to escape through her fingers.
“What's so funny!?”
Kuruma yelled with uncharacteristic anger, and Tsukiyo gave Yuma a sidelong glance, as if asking “You get it, right?”
“That isn't true, Mr. Kuruma,” Yuma said in a whisper. “This woman recognizes no contradiction between wanting to be a great detective and killing people.”
“What... What are you saying...? I don't understand...”
Kuruma held his bald head in both hands.
“Certainly, she is obsessed with being a great detective, and continues to pursue that dream. But 'being a great detective' itself isn't the root of her obsession. It was born of a compromise.”
“Compromise? Then what does Ms. Aoi really want?”
Sakyo asked nervously.
“To meet a great detective. During her painful childhood, she escaped into the world of mystery. She had always longed to meet a great detective. But great detectives aren't as common in real life as they are in books. So she had no choice to become one herself. But deep down, she still longed to encounter a great detective. Like a girl waiting for her prince charming.”
“Yuma, telling a woman she's waiting for prince charming is a sure way to piss her off.”
After Yuma apologized, Tsukiyo raised one end of her lips.
“But, well, you aren't wrong. I've always dreamed of meeting a great detective. I've been waiting for that day for a long time.”
“How does that lead to murder?”
Kuruma looked at Tsukiyo as though she was some unknown lifeform.
“Because a great detective can't exist in a vacuum.”
Kuruma frowned at Yuma.
“Please stop talking in zen riddles. I feel like my head is about to explode.”
“Oh, sorry. Ms. Aoi told me yesterday. Great detectives are weak, passive beings who can only wait for difficult cases to occur. In other words, for a great detective to exist, there must be difficult cases for them to solve.”
Kuruma and Sakyo's faces stiffened in a way that clearly communicated that they understood. Yumeyomi was the only one who blinked repeatedly and said “What do you mean?”
“For Ms. Aoi, who wanted to meet a great detective more than anything in the world, creating difficult cases herself and looking for people to solve them was a completely natural act. She wanted to create a great detective herself.”
Unable to accept that answer, Yumeyomi's mouth dropped open. Next to her, Kuruma began to tremble violently.
“That's... impossible. Even if it's theoretically possible, there's no way she could kill someone for a reason like that without even hesitating...”
“No, she could have. Because... She's done it before.”
“Done it before...?”
Kuruma trembled even harder.
“Do you remember, Mr. Kuruma? After dinner on the first day, while everyone was relaxing in the game room, Mr. Kagami got involved with us. He brought up several unsolved mysteries that Ms. Aoi had refused to investigate. And she replied 'even a great detective can't play two roles'.”
Yuma continued with a sideways glance at Tsukiyo.
“'One person playing two roles'. At the time, we all understood her to mean that she was busy with another investigation, but that's a strange way to put it. What she really meant when she said that was...”
Yuma paused, then solemnly declared:
“A person can't play the role of detective and culprit in the same case.”
“Wait, then...”
The color drained from Kuruma's face.
“Yes. The disappearance of the passenger from the jumbo jet, the swimmer who burned to death in a pool, and the destruction of dinosaur fossils from a museum. The culprit of those three shocking incidents was the great detective Aoi Tsukiyo herself. Isn't that right, Ms. Aoi?”
When Yuma called out to her, Tsukiyo looked off into the air.
“That's a pretty interesting story, Yuma.”
“You're denying it?”
“No, that's not what I meant. But I don't like that the only evidence is what I said about 'playing two roles'. When a detective presents a theory, it needs to be more convincing.”
“Then what about your origin story as a great detective?”
“My origin as a detective?”
Tsukiyo's voice lowered slightly.
“Yes, the incident that made you want to become a great detective. The case of your parents' brutal murder in a locked room.”
The corners of Tsukiyo's mouth raised just a bit.
“Continue,” she said.
“You were disappointed no great detective appeared to solve your parents' case, so your resolved to become one yourself, and you succeeded. But you also said your parents' case was still unsolved, and that you're still waiting for a great detective to come along and solve it. Isn't that strange?”
“How so?”
Tsukiyo gave a slight, provocative tilt of her head.
“You became a great detective. Surely, it's only natural that you would try to solve your parents' case yourself. And yet, for some reason, you're still waiting for another great detective to appear.”
“And why do you think that is?”
“Because one person can't play two roles.”
A broad, earnest smile spread across Tsukiyo's face. It was the sort of expression a person could only make when, for the first time in their life, they'd found someone who understood them.
“Then, Ms. Aoi...”
Kuruma's mouth silently slid open and closed like a goldfish on land.
“Yes. Ms. Aoi brutally murdered her own parents and turned the crime scene into a locked room. She though that by doing so, she would be able to meet a great detective like the ones she'd admired since childhood.”
“You mean she killed her own parents just for that?”
“No, I don't believe that was it at all. Ms. Aoi told me that, before her parents' murders, she'd been horribly persecuted and spent most of her time locked in her room. I'd thought for sure she was bullied at school, but thinking back, Ms. Aoi's told me about her school days, and none of her stories involved bullying. In other words, the object of fear that had trapped her in her room probably wasn't her classmates... but her parents.”
“...Abuse.”
The moment Kuruma muttered the word, a dark shadow fell across Tsukiyo's face for just a moment.
“I don't know exactly what they did, but whatever the case, Ms. Aoi killed her parents to escape a harsh environment. She locked the room afterwards because she wanted to meet a great detective. But the great detective never appeared, so she filled the void in her heart by becoming a great detective herself. But she couldn't give up on her dream of someday meeting a great detective, so she continued her activities, wearing two different faces.”
“What were the two faces...?”
Kuruma muttered like a lost soul.
“One is the public face of Aoi Tsukiyo, the great detective who solves difficult cases. But while doing her honest best at that, she also committed mysterious crimes herself, waiting for the day when a great detective would appear who could solve them. In other words, you could call her other face...”
Yuma looked at Tsukiyo with a smile of genuine happiness, and softly spoke her real name.
“The great criminal, Aoi Tsukiyo.”
“A great criminal...”
Kuruma and Sakyo simultaneously muttered the unfamiliar phrase.
“A great detective is born when they solve a difficult case that only someone with superhuman intelligence could solve. One excellent 'great criminal' can give rise to many great detectives. For someone who wants a great detective to exist at any cost, becoming one is an extremely rational choice. And Ms. Aoi had the combination of intellect, drive, and... abnormality to make it happen.”
Yuma clasped his hands together.
“Come to think of it, when I called myself Moriarty after my confession, you had an unusually strong reaction. That was because you took pride in having already taken the title of Moriarty, that is, the worthy rival to great detectives, wasn't it?”
Yuma spoke calmly, never taking his eyes off Tsukiyo. Tsukiyo smiled. It was a smile full of genuine happiness.
“Thank you, Yuma. Thank you so much. This is the first time anyone has ever understood the real me. You're the best Watson I could have asked for.”
After wiping the tears from her eyes with the back of her hand, Tsukiyo took a deep breath to steady her excited nerves.
“So, what are you planning to do next?”
“Next?”
“That's right, Yuma. You're still only playing at being a great detective right now. A great detective isn't just someone who knows the truth. You can't become a great detective until you close the case.”
Tsukiyo put more weight on her knee resting on Sakaizumi's neck. A groan of pain escaped from his mouth.
“I have a hostage, so that gun you have is useless. Now, how are you planning to bring me in? Did you really think I'd obediently surrender just because you know the truth?”
“The police will be here soon! Just give up!”
Yumeyomi screamed, cowering behind the others. Tsukiyo looked shocked.
“Ms. Yumeyomi, The Glass House Murders was just an idea for a story from Mr. Kozushima's brain. It was a work of fiction. Nobody actually called the police, and that story about the road being blocked by an avalanche was made up. Didn't you realize?”
“...That doesn't change your situation,” Kuruma said in a hushed voice. “It's only a matter of time before the people close to us realize they can't contact us and come looking. When they do, the police will be alerted. All of the crimes you've committed in the Tower will be exposed. There's no way out for you.”
“Mr. Kuruma, I am a master criminal. An expert in the field, if you will. You really think I haven't thought that far ahead? Even if Yuma didn't uncover the truth, a proper forensic investigation would find it obvious that The Glass House Murders was a work of fiction and that I'd committed the murders. Of course, I've already accounted for that.”
Tsukiyo shifted her eyes from Kuruma to Yuma.
“I think Yuma's realized. I've told you what I have in my bag of tricks.”
––If I wanted to, I could make a remote detonation device out of things in this tower.
The words he'd exchanged with Tsukiyo on the second day suddenly rushed back to him. Alongside the sight of the empty shelf he'd seen in the power room a few hours ago.
“You made a bomb!?”
Yuma's voice went up high, and Tsukiyo took a palm-sized object from her pocket. She removed the cover from the black rectangle, revealing a bright red button.
“If I press this, a large amount of gasoline will explode in the main kitchen, engulfing the entire Glass Tower in flames. I never planned on killing anyone else, Mr. Kuruma. I had originally planned to have you all testify about The Glass House Murders and frame Yuma and Mr. Kagami as the culprits behind the real murders. It really is too bad.”
Yumeyomi collapsed on the spot, not even able to scream. She desperately crawled for the entrance.
“Don't move!”
Yumeyomi gave a violent start when Tsukiyo yelled, and turned around on all fours. Tears overflowed from both her eyes, smudging her heavy makeup until she looked like a clown.
“If anybody moves, I'll press the button. If you don't want that, then just hold still. Now then. I'm sorry to have kept you waiting, Yuma. I'd like to hear you, as a great detective, tell me: How would you overcome this difficult situation?”
Tsukiyo's cheeks were flushed. She was as excited as a child about to leave on a field trip.
“If things continue like this, you'll walk out the front door, lock us in the Glass Tower, burn us to death, and disappear into the night.”
“It's the best option for me. Nobody will be left who knows I'm a great criminal, and I'll be able to continue on with both my faces: the great detective and the great criminal.”
“Coward.”
“What?”
Tsukiyo's cheek twitched.
“I called you a coward. You overwrote The Glass House Murders and turned it into a real honkaku mystery. As a detective, I solved it. Mystery is a game of pure intellect. In other words, I challenged you, great detective to great criminal, and I won. Even an elementary schooler knows that the winner of a game gets a prize and a loser gets a penalty.”
“You didn't completely beat me. You didn't plan for the bomb.”
“Which is why I'm not asking you to turn yourself in after releasing us all. Let's find a compromise.”
“A compromise... Interesting.”
Tsukiyo's steadily hardening expression suddenly softened.
“Well then, let's negotiate. What is your proposal, Yuma?”
“Let everyone out of the Glass Tower except me.”
“You mean I have to guarantee everyone's safety except yours? But then the police will learn that I'm a great criminal.”
“That's the punishment. It isn't so bad. You decided yesterday you'd rather live as a great criminal than a great detective.”
“What do you mean?” Tsukiyo asked, playing dumb.
“'Do what you need to do. Become your true self once again.' That's what I said to you when you were feeling down after the third incident yesterday. Afterwards, you regained your spirit. Of course, what I meant was 'do what you do as a great detective', but that isn't how you took it. You decided that your true self was a great criminal. And so, you decided to take over The Glass House Murders and use your position as a meta character to create an artistic honkaku mystery.”
Yuma took a deep breath.
“Really, I gave you a push when you were wavering. It's my fault you resolved to live as a great criminal.”
“So you're saying you'll take responsibility for that by staying with me in the Tower?”
“Yeah, that's right. What do you think? It's not a bad idea.”
“You played my Watson in The Glass House Murders and the great detective in the story I wrote, so we'll face the climax together. No, that isn't a bad idea at all. Well then.”
Suddenly, Tsukiyo threw the detonator at Yuma. Yuma's eyes bugged out as he carefully caught the detonator from its wide arc in both hands. The moment he breathed a sigh of relief that he hadn't dropped it, he felt a blow to his stomach. As he felt to the ground, he realized that Tsukiyo had run at him the moment the detonator left her hand, running headlong into him.
Tsukiyo grabbed the shotgun and the detonator off the floor and pointed them both at Yuma, who was coughing violently.
“I accept your terms! Mr. Kuruma, I'm sorry, but please take Mr. Sakaizumi, Mr. Sakyo, and Ms. Yumeyomi and leave through the front door. It's dangerous, so please keep a sufficient distance. I'd recommend evacuating at least to the parking lot.”
“But Dr. Ichijou...”
Kuruma was extremely hesitant. It was written all over his face.
“I'll be fine, just go! This is between me and her!”
Yuma yelled, clutching his pained stomach.
Yumeyomi shouted “Let's hurry!”, urging Kuruma on. With a pained expression, Kuruma let Sakaizumi lean on his shoulder and accompanied Sakyo to the entrance. Yuma gave a firm nod as Kuruma finally left.
The four of them disappeared, and the door slammed shut with a heavy bang.
“Now we're finally alone. We can talk calmly.”
“I don't think it's possible to talk calmly with a gun pointed at you, though.”
Yuma gave a smile. Strangely, he felt no fear. If anything, being alone with Tsukiyo was comfortable.
“So, Yuma, what sort of finale should we give this story? No matter how great a trick a mystery has, it will never be called a masterpiece unless it has a good final scene.”
“Deciding that is your job. It's your story. But let me say one thing before the curtain comes down.”
Yuma narrowed his eyes.
“Thank you.”
“You're thanking me? For what?”
Tsukiyo blinked in confusion.
“You gave me a chance. You could have burned down the Glass Tower immediately and not given me any time to solve the mystery. But you went out of your way to give me hints. You were the one who left the model of the TRIDENT, the book on genetic engineering, and the copy of Think of a Number in the display room. You left me a lot of hints, since you knew I'm nowhere near smart enough to be a great detective. That's the only reason I was able to find the truth.”
“It would be sad if the story I worked so hard on ended without anybody even trying. You said I took over The Glass House Murders like it was no big deal, but it was actually a lot of work. I had to change Ms. Tomoe's body into a wedding dress, crush the rat poison into tiny pieces, and put them into capsules. All while you were snoring away without a care in the world.”
Imagining Tsukiyo struggling to fit tiny pieces of rat poison into small capsules, Yuma unintentionally smiled.
“See, you can relax even with a gun pointed at you. Because we're friends.”
Tsukiyo spoke playfully. The two of them looked at each other, then, simultaneously, they burst into laughter. For some reason, they both felt cleansed.
“By the way, Ms. Aoi, what were you planning to do when you found a great detective?”
After the fits of laughter subsided, Yuma asked.
“What I'd do?”
Tsukiyo repeated it, curious.
“Meeting a great detective means the crimes will be exposed. Since you're a criminal-”
“Great criminal.”
“Alright, alright, so what were you planning to do, great criminal?”
“What would I do...? I suppose I hadn't quite thought things through. Hmm, what was I planning to do when I met a great detective?”
Putting a hand on her chin, Tsukiyo thought about it seriously.
“May I offer my theory?”
Tsukiyo blinked a few times, then grinned at him.
“Of course, Yuma. You are the great detective.”
Yuma told the blushing Tsukiyo
“Well then I guess I have to. You wanted to go over the Reichenbach Falls with the great detective, didn't you?”
“...You mean I wanted to commit suicide together with them?”
“Yes, that's right. When I called myself Moriarty after being arrested for the murder of Mr. Kozushima, you had a strong negative reaction. That's because, subconsciously, you pride yourself on being 'Moriarty'. You dream of dying alongside a great detective. That's why you see yourself as Moriarty, not Hannibal Lecter or Magata Shiki.”
“Me... and a great detective...”
Tsukiyo mumbled to herself in monotone as her eyes wandered. It was possible that if he jumped her now, he could wrestle the gun and the detonator from her. But Yuma didn't move.
Tsukiyo's eyes began to moisten. Her face filled with total ecstasy.
“Yes, that's right. That's right. I've always wanted to die together with a great detective. I wanted to fight with my greatest rival and die together.”
Tsukiyo looked at Yuma with eyes unclouded.
“Thank you, Yuma. If I didn't have my hands full, I'd grab you and kiss you.”
“You told me you weren't looking for a romantic partner.”
“I'd even be willing to break that taboo under the circumstances. Besides, our relationship as partners ended this morning.”
Tsukiyo licked her lips with a crimson tongue. Her seductive gestures exuded such a powerfully sensual aura that Yuma felt a shiver down his spine.
“...To be honest, it's an extremely tempting offer, but now isn't the time.”
“Yes, unfortunately, I don't have the time to embrace you. Besides, in this glass building, we're completely visible from the outside. I don't have that kind of fetish.”
For some reason, Yuma felt fondly about these moments of banter. Deep within his heart, he knew he wanted to be with her.
But no matter how attractive she was, she was a serial killer, and he was a doctor. They would never be compatible.
Yuma smiled.
“Well, I don't really want to leave now, but let's get this over with. Either shoot me or press the button.”
“You're letting me choose?”
“Of course. You've taken over The Glass House Murders and become the master of the story. You have a duty to bring this mystery, cruel yet ephemeral and beautiful as glasswork, to an end.”
“Either way, you'll die.”
Yuma looked up at the chandelier hanging from the ceiling.
“Guess so. Mr. Kozushima died without me having to dirty my hands. My sister will be able to get her treatment without being slandered as a relative of a murderer. I've already achieved my ideal outcome. And besides...”
Yuma exhaled the air that had built up in his lungs.
“Even if I didn't actually kill him, I gave Mr. Kozushima that capsule with clear murderous intent. I need to face my punishment.”
“You're a good man, Yuma. So, great detective, will you accompany me over the Reichenbach?”
“I'm no great detective. I'm pathetic, an impostor who can only win when the culprit gives me a handicap. I don't think I'd ever be a match for a great criminal, but if you'll have me, I'll gladly accompany you on your journey to hell.”
Yuma thought dying with his hand in Tsukiyo's wouldn't be so bad.
“Thank you, Yuma. I'm glad I met you.”
Tsukiyo lowered the gun and raised the detonator up towards the ceiling.
“Oh, wait one moment.”
When Yuma called out, Tsukiyo cocked her head to the side, thumb still on the button, and asked
“What is it?”
“Will you tell me the title of your story?”
“Title?”
“That's right. You took over The Glass House Murders and turned it into a honkaku mystery entirely your own. It's now something completely different from The Glass House Murders. That's why, before the end, I want to know what it's called. I want to engrave into my mind the title of the story where I became a great detective and lost my life.”
“Yes, for a honkaku mystery novel, the title is important. It can make a major impact on the sales numbers. But... To be honest, I hadn't thought of one.”
Tsukiyo wrinkled her brow and stared at the floor.
“Earlier, Yuma said it was a honkaku mystery as beautiful as glasswork, so Murder in Glasswork would be... No, since the story is set in a strange mansion that's become a closed circle, a title that evokes that sense would be better... All great works of honkaku mystery have words like 'murder' or 'tragedy' in their names...”
Muttering to herself with a dead serious face, Tsukiyo pondered for several seconds, then slowly raised her head.
“Have you decided on a title?”
“Yeah. I have.”
Smiling happily, Tsukiyo announced it.
The title of this story.
“The Glass Tower Murders.”
Tsukiyo's thumb pressed the red button.