Head On Home...

Day Three

1

“Ellery Queen's The Egyptian Cross Mystery and Barnaby Ross's The Tragedy of Y, both published in 1932, are two great masterpieces. When readers disagreed on which was better, Queen and Ross both appeared at a lecture wearing black masks and had a public debate full of vitriol. But a few years later, it was revealed that 'Barnaby Ross' was a second pen name used by Ellery Queen, and the two works actually had the same author. That raised the question: who were the two people who had debated at the lecture? Yuma, do you know the answer?”

“...Frederic Dannay and Manfred Lee.”

Yuma answered with a sigh, and Tsukiyo pointed a finger at him and said “Correct.”

“Ellery Queen was itself a collaborative pen name used by Dannay and Lee, who were cousins. In other words, the works of Ellery Queen were created by the two of them, which is how they were able to have a debate with themselves. Wow, you're good, Yuma. Even many hardcore mystery buffs don't know that story.”

“Thanks.”

“It actually isn't rare for authors to collaborate under single pen names. The first Japanese author to come to mind is Okajima Futari, who won the 28th Edogawa Rampo prize for Dark Brown Pastel. Of course, Okajima Futari made it known from the beginning that they used a joint pen name, even incorporating the character for 'two' into the name...”

Yuma listened to Tsukiyo's endless stream of mystery trivia while holding his head, which was throbbing with a dull ache. Tsukiyo had woken him up with a loud knock at five in the morning, sat down on the sofa, crossed her legs, and announced “and now, on to the mystery.”

While he was completely done with her selfish behavior, Tsukiyo's deductions were vital if Yuma wanted to learn who had killed Oita in time, so Yuma forced himself to get through his morning routine quickly. But as soon as he got dressed and sat down to listen, Tsukiyo veered off on a series of tangents and disappeared down the rabbit hole of mystery trivia, so she hadn't actually delivered any deductions.

Since Kozushima's dying message was related to The Tragedy of Y, the conversation had somehow turned to Ellery Queen, and from there rapidly descended to irrelevance.

“Come to think of it, after Okajima broke up, Inoue Yumehito, who continued as a solo writer and was a fan of the Beatles, formed a cover band with Shimada Soji, who was also a fan of the Beatles-”

“Ms. Aoi. Stop.”

Unable to take it any longer, Yuma interjected. Tsukiyo, who had been having a good time, pouted and asked

“What?”

“We can talk about mystery trivia later. Tell me about the case.”

Tsukiyo's eyes unfocused for a few seconds, then she exclaimed “Right, the case!”

Had she actually forgotten? Feeling his soul leaving his body, Yuma slumped over and looked at Tsukiyo.

“So? Have you learned anything new? Say... any idea who the culprit is?”

“Nope, nothing.”

Yuma's shoulders slumped even further when she answered without hesitation. But Tsukiyo continued without a moment's pause.

“But I think I have an idea how the locked room was created.”

“Really!?”

Yuma was suddenly on his feet.

“How did they do it? How did they create that locked room? Did they set the fire to burn Mr. Oita's body after all? Actually, how did they start the fire in the first place?”

As he continued bombarding her with questions, Tsukiyo looked out the window.

“It looks like it's going to snow again. Even though it was fine yesterday...”

“Ms. Aoi!”

“Don't get upset. Everyone knows talking about the weather is a basic element of the art of conversation. There are still a few things about the locked dining room I'm not sure about. As a great detective, I can't go public with an incomplete theory.”

“Now is no time to be slacking off. When will-”

The moment Yuma said that, a deafening siren echoed through the room.

“There is a fire in the sub-kitchen. There is a fire in the sub-kitchen. Evacuate at once.”

As the artificial voice went on, the motors attached to the ceiling all started at once, opening all the windows.

“You're kidding me! Again!?”

Feeling a horrible sense of deja vu, Yuma shot to his feet. Tsukiyo grabbed his hand.

“Yuma, let's go to the first floor.”

Perhaps what had happened in the dining room yesterday had happened again. Even if that wasn't the case, if there was a fire, they needed to put it out immediately. “Right,” Yuma nodded, and he and Tsukiyo ran down the glass staircase. When they reached the first floor, they went straight to the door to the sub-kitchen without a single detour.

Yuma grabbed the doorknob and pulled as hard as he could. Unlike yesterday, there was no resistance, and the door flew open. The sprinklers were already spraying water all over the dimly-lit kitchen. There were no flames to be seen. Perhaps they'd already been put out. Tsukiyo pressed the switch next to the door. The washed-out light of the fluorescent lights filled the sub-kitchen.

The sprinklers chose that moment to cut out. Yuma heard footsteps behind him. He turned around to see five people arriving one after another: Kuruma, Kagami, Sakyo, Sakaizumi, and Yumeyomi.

“What's happened!?”

Yumeyomi shrieked hysterically, despite being out of breath. Her face was filled with terror. She was probably imagining the worst case scenario: another dead body in a locked room.

“We don't know, we just got here.”

“There isn't a body inside, is there?”

Kagami asked in hushed tones. The atmosphere in the room suddenly tensed.

“It doesn't look that way at first glance. But there are blind spots in the room. We need to investigate thoroughly.”

When Tsukiyo replied, Kagami said “Let's hurry up, then” and strode into the sub-kitchen. Yuma followed Tsukiyo through the door, carefully crossing the floor slippery from the sprinklers. After a moment, Tsukiyo went “Ah!” His heart leapt, thinking a body had been lying there. However, what Tsukiyo was indicating was the remains of a candle on the kitchen table.

“It looks like this is what started the fire.”

“A candle?”

Sakyo peered over Tsukiyo's shoulder.

“Yes, it is. There also appear to be the remnants of burnt tissue paper lying around it, and a smell of petroleum.”

Tsukiyo brought her well-formed nose up to the table.

“They probably left a large amount of tissue paper soaked in kerosene at the base of a lit candle. The candle shortened as it burned itself down, and eventually, the fire spread to the tissues and created a pillar of flame. That must have been what triggered the sprinklers.”

“It's a very simple automatic ignition device,” Kuruma observed, looking at the remains on the table. “I wonder how long it took the tissue to catch fire after the candle was lit?”

“There isn't much melted wax left, so it would probably only be about twenty or thirty minutes. Does that sound about right to you, Mr. Kagami?”

Kagami, having been called out to Tsukiyo, looked dispassionately at the candle and said

“That's probably about it, yeah.”

“So, someone set a device to make the sprinklers go off after twenty to thirty minutes. But why? What purpose would that have served...?”

Kuruma put a hand to his bald head.

“It doesn't look like they were leading us to a body like yesterday. At the very least, there isn't any body in this sub-kitchen.”

Looking around the room, Tsukiyo placed a finger to her slender jaw.

“Perhaps gathering us all here was their goal. If there was a fire, everyone staying in their rooms would come out.”

“Um... Where's Madoka?”

Sakaizumi asked timidly. Come to think of it, Madoka wasn't anywhere to be seen.

“She's still in her room, isn't she? That maid looked scared out of her mind,” Kagami said disinterestedly.

“That can't be. The fire alarm went off. Surely everyone would have come out. Look, even the fortune teller lady came out after saying she was going to stay in her room.”

Yumeyomi's expression darkened at Sakaizumi's observation.

“He's right, it is strange that she hasn't come down after all this commotion. We should go and check on her.”

Following Kuruma's suggestion, everyone hesitantly left the sub-kitchen with Sakaizumi out in front and climbed the glass stairs to the landing before the Sixth room. Sakaizumi gave the knob a pull, but it appeared to be locked and the door didn't open.

“Madoka! Madoka, are you okay?”

Sakaizumi pounded his fist on the door. The heavy sound was loud enough to echo down the stairs, but there was no response.

“Hey, I don't care if you wanna stay in that room, but at least answer!”

Kagami pushed Sakaizumi away and yelled, but there was still no response. Everyone began to grow uneasy.

“If you don't answer, I'll break down this door! Is that what you want!?”

Kagami lost patience and kicked the door. However, the polished metal door didn't move. Kagami groaned and began hopping on one foot.

“That door isn't like the one to the dining room; there's no way to break it down. We'll need to unlock it. Mr. Kuruma, Dr. Ichijou.”

Yuma straightened his back when his name was suddenly called.

“Do you still have the keys to the safe? The one containing the master key.”

“Oh, yes, it's right here.”

Yuma took the key from his pocket. Kuruma also held up a key, saying “I have mine, too.”

“Then let's go to the underground storeroom and get the master key.”

“Alright. Dr. Ichijou, let's go together.”

Yuma was about to go down the stairs with Kuruma when Kagami shouted

“Wait!”

“What is it? We have to hurry.”

Yuma protested, holding his sore ear, and Kagami scoffed.

“We're all going to the underground storeroom. We need to make sure the master key's really in the safe. It's possible what you locked up yesterday was a fake.”

“...Do whatever you want.”

Getting sick of Kagami's overly-suspicious attitude, Yuma descended. At Kagami's instruction, the others followed him. When they arrived in the underground storeroom, Tsukiyo ran up to the safe before Yuma could reach it and grabbed the handle. Of course, the door didn't open.

“Come on, Yuma, hurry,” Tsukiyo beckoned.

“I know,” Yuma replied, approaching the safe. He and Kuruma inserted their keys into the keyholes.

“Alright Mr. Kuruma, on three. One, two, three.”

On his signal, Yuma and Kuruma turned their keys. The lock was undone with a clack. Yuma turned the handle and the door noiselessly slid open. Inside was the master key engraved “Zero”.

A moment later, Sakaizumi pushed Yuma to the side, grabbed the master key, and started running. He was too worried about Madoka to hold still. “Ah, wait!” Kagami immediately started after him. Yuma and the others jogged after them.

When they were back in front of the Sixth room, Sakaizumi was trying to open the door. But his hands were shaking so badly that he couldn't fit the key in the lock.

“This is embarrassing. Want me to help?”

Kagami said mockingly. Sakaizumi glared at him with bloodshot eyes and said

“Shut up!”

“Oh, scary. In that case, why don't you hurry up and open the door already?”

Ignoring Kagami, who was raising his hands in mock surrender, Sakaizumi finally managed to unlock the door and immediately threw it open. A cold wind blew into the stairwell. Yuma gasped at the sight burned into his retina.

Madoka lay on the bed by the window.

Tomoe Madoka was wearing a white wedding dress with the chest stained red.

“Ahh... Madoka... Madoka!”

As Sakaizumi ran to Madoka, crying out in pain, Kagami casually grabbed the back of his collar and pulled him back.

“What are you doing!?”

Kagami glared at Sakaizumi, who had fallen to the ground and had tears in his eyes.

“She's obviously dead. That means this room is a crime scene. And I've told you all countless times now not to disturb crime scenes.”

“Now isn't the time to say things like that...”

“You're the one who shouldn't be saying things!” Kagami roared, loud enough to shake the glass of the walls. “The police will be here tomorrow to start the investigation. Then we'll learn the identity of the culprit who killed these three people. Not that there are many suspects left.”

Dimpling his unshaven cheeks, Kagami glanced at everyone gathered outside the door. He was about to enter the room when Tsukiyo, graceful as a cat, slipped past him.

“This wedding dress consists of a separate top and bottom. It must be the same one that was on display in the display room, the one used in the filming of Sherlock: The Abominable Bride.”

Tsukiyo looked at Madoka's form, lying on the bed.

“Hey, don't go in there without permission!”

Ignoring Kagami's yelling, Tsukiyo looked around the room.

“I don't see the key to the room. Could the culprit have taken it when they left?”

Tsukiyo muttered to herself, and Sakaizumi, still sitting on the floor, spoke in a weak voice.

“Look at the thing on her head.”

“The thing on her head? You mean her maid's headdress?”

As Tsukiyo tried remove the headdress from Madoka's head, another hand reached out from the side.

“Hmm? There's a zipper here. Is that it?”

Kagami tore off the headdress and said that. Sakaizumi watched him with lifeless eyes.

“Madoka always kept her key in there... She was so careless... she always said how she lost things easily...”

Kagami opened the zipper, and the key fell to the floor. Tsukiyo quickly snatched it up, as if taking revenge for earlier.

“Hey, don't touch that!”

Kagami shouted, but Tsukiyo ignored him and approached Yuma and the others, a serious expression on her face.

“This key is engraved 'Sixth'. It must be the key to the Sixth room.”

Tsukiyo removed the master key from the keyhole and inserted the key she'd taken, twisting her wrist. With a clack, the lock protruded from the door.

“The key to the room was inside Madoka's headdress, and the master key was in the safe. So how could the killer have locked the door after leaving the room?”

Tsukiyo muttered to herself.

“They didn't leave!” Yumeyomi suddenly shrieked. “The murderer who killed the maid has been in this room the whole time!”

“Hey, what are you talking about? Did you forget? We were all gathered together in the sub-kitchen earlier.”

Kagami didn't understand what this woman was talking about.

“No! The culprit isn't one of us! I've said it all along. There's someone else hiding in this Tower. They killed the maid, and now they're with us here!”

“You mean the culprit is still in this room?” Kuruma asked.

Yumeyomi nodded several times.

“Of course they are! They're hiding somewhere! We need to get out of here!”

The air tensed. Yuma quickly scanned the room. However, nobody was there. Kagami also looked wary, checking under the bed, behind the furniture, in the bathroom, and so on.

“There's nobody here,” Kagami said, scratching his head as he emerged from the bathroom. “Geez, I don't care if you're a psychic or fortune teller or whatever, but stop scaring people with your weird delusions.”

“They aren't delusions! Why don't you believe me!? There is a dangerous presence in this Tower. I sense something evil...”

Yumeyomi was sobbing between words. The abnormal situation had pressed her to her limit. In extreme situations, panic spreads more efficiently than any disease.

That was dangerous. If things continued like this, it was only a matter of time before their group cohesion completely broke down. Yuma could fear the atmosphere boiling over, and he was afraid of what came next.

The next moment, a loud bang shook the air. Everyone who had been looking around as though begging for help turned to the source of the sound, Tsukiyo, who stood with her hands pressed together at chest level.

“Everyone calm down. Let's talk this out rationally.”

Tsukiyo spoke quietly, in stark contrast to her usual cheer. Her expression, too, was flat and lifeless.

“If we panic, we'd only be playing into the culprit's hands. First, we need to investigate the scene.”

Her voice was completely hollow.

“The door was locked, and the only key was found inside the room. The culprit wasn't found in the room. So, we need to ask ourselves how the one who killed Ms. Tomoe disappeared from the locked room.”

“Maybe they went out that window?”

Sakyo nervously pointed to the window. Because the fire alarm had gone off, all the windows in the Tower were open about 45 degrees from the ceiling to the outside.

Tsukiyo glided over to the window and peered out from next to the bed. Kagami called out “Hey!”, but Tsukiyo ignored him.

“If someone had tried to climb out the window, they would have left hand and foot prints on the glass. But at first glance, I don't see any. And...”

Tsukiyo took her smartphone from her suit pocket and began lazily taking pictures of the view outside the window.

“The exterior walls of the Tower are covered in smooth glass. Unless the culprit is a gecko, it would be impossible to climb them without tools. And if someone used tools, they would have left marks on the exterior walls. But no matter how hard I look, I can't see any such traces. The culprit who murdered Ms. Tomoe didn't go out this window.”

“But if they couldn't have used the keys, and they couldn't have used the window, then this room is...”

Kuruma's voice trembled. Tsukiyo gave a grave nod and finished the line.

“Yes. A locked room.”

“Locked room...”

The words escaped Yuma's mouth.

Not again. Another person had been murdered in a locked room. What on Earth was happening in the Tower? Yuma began whispering to himself, running his hands through his hair.

“Three murders in three locked rooms? I feel like I've been trapped in one of my own honkaku stories.”

Kuruma covered his eyes and shook his head helplessly. Tsukiyo suddenly called out to him.

“You might not be imagining things.”

“What?”

Kuruma's brows furrowed.

“We might actually be characters in a story without even realizing it. Characters in a closed circle honkaku mystery novel.”

“What... What are you saying...?”

Kuruma's looked like his world was collapsing. Yuma was just as confused.

Tsukiyo had said something similar yesterday, but back then, it was clear she was joking. However, from the deathly serious attitude Tsukiyo had now, it was like she really did believe that she was the protagonist of a novel.

He had thought Tsukiyo was enjoying being in this situation. But it may have been that she was forcing herself to act like a stereotypical great detective. Beneath the mask, fear could have been eroding away her heart the same as everyone else's.

She was playing the clown, embracing the role of “great detective” in the face of the real life honkaku mystery they found themselves in now. It was possible that the woman called Aoi Tsukiyo had managed to become a character in a story.

“What the hell are you talking about!? This isn't some novel, this is real life. Wake up!”

Kagami yelled at Tsukiyo, and her blank eyes suddenly refocused.

“Oh... I'm sorry. I... I need to examine Madoka's body.”

Tsukiyo staggered her way over to the bedside and she put her hands on Madoka's skirt, but Kagami roughly yanked her by the shoulder.

“How many times do I have to repeat myself? Amateurs should stay out of crime scenes. I am absolutely not letting you touch a dead body. Especially not after you went all cuckoo on us earlier.”

Tsukiyo had no strength left in her body and staggered back. She lost her balance, and Yuma hurried over to support her.

“What are you doing, placing your hands on a woman!?”

Kagami scratched at his neck, embarrassed by Yuma's protest.

“I didn't mean to pull her hard. I thought a tall broad like her would be able to take it.”

“It's fine, Yuma. Don't worry about me.”

Still leaning on Yuma, Tsukiyo could barely speak.

“He's right. I shouldn't look at the body in my current state. Mr. Kagami, please check for me. Looking at her wounds, it looks like Madoka was...”

“Yeah. She was tortured before she was killed.”

The moment he said the word “torture” in his hushed voice, the temperature in the room dropped below zero.

“Tortured...?”

Yuma forced through the back of his throat.

“Yeah, that's right.”

Kagami lifted the skirt of the wedding dress.

“Hey, what are you doing-”

Sakaizumi was about to protest, but his complaint died on the vine. Yuma couldn't believe his eyes. Even from a distance, he could see dozens of red slashes running along her pale thighs.

“Her thighs must have been cut up with a knife. There are also traces of a gag around her mouth, probably to stop her from screaming.”

Even Kagami could recognize that it wasn't right to leave the thighs of a young woman exposed, living or dead, and quickly dropped the skirt back down.

“That's... so horrible... Madoka...”

Sakaizumi covered his face with both hands, and his shoulders began to shake.

Kagami pulled on the collar of Madoka's wedding dress, wet with dark red liquid, and peered at her chest.

“The direct cause of death was a stab wound. There's one in her chest here. It's likely it pierced her heart. Instant death, or near enough. They probably tortured her for some information, then disposed of her once she was no longer of any use. Judging by the fact that the body's still warm and the blood hasn't dried, it can't have been long since she was killed. Maybe twenty or thirty minutes.”

Kagami muttered under his breath, then turned to look at Yuma and the others.

“Any of you have an alibi for between twenty and thirty minutes ago?”

Yuma took a sidelong glance at Tsukiyo. She showed no signs of asserting her alibi. She had been talking about the incident with Yuma in the Fourth room for nearly two hours.

Was she still trying to avoid cornering the culprit like she had yesterday? Or was she just in shock? Unable to decide, Yuma kept his mouth shut. Nobody else spoke, either.

“So nobody has an alibi? Well, that's fine. To be honest, it doesn't really matter who has an alibi. I already know who the culprit is.”

Kagami's casual announcement sent ripples through the room.

“You know who the culprit is!?”

Yumeyomi raised her voice. Kagami gave a hearty nod.

“Of course. You could have figured it out for yourself, if you'd given it some thought. The door to this room was locked, and the vic had the key. And there was only the body in the room, no signs of the perp, and as the self-proclaimed great detective explained earlier, no way to escape out the window. So, how did the perp manage to create one of the 'locked rooms' you mystery-loving freaks are so obsessed with? There's only one answer.”

“How did they do it? Tell me!”

“It's simple,” Kagami said proudly. “He used the master key.”

“The master key? But it was in the safe.”

Yumeyomi was clearly dissatisfied with his explanation.

“Yeah, that's right. But we didn't activate the combination lock so we could get it back if something happened.”

“Then...”

Yumeyomi face twisted with fear, and she stepped away from Yuma.

“That's right. The writer and the doc who had the keys are accomplices.”

When Kagami pointed at him, Yuma just stood there, not immediately comprehending what he'd been told. He turned to Kuruma and saw him frozen with a similarly stunned expression.

“I don't know why, but those two worked together to brutally murder Kozushima, the butler, and the maid. Maybe they were planning to take out the rest of us in time.”

“Hold on a moment.”

Sakyo spoke up in place of Yuma and Kuruma, who were frozen in place.

“What about the second murder? How did they lock the dining room and set the fire inside?”

“Who cares?” Kagami waved his hand, annoyed. “Once we have these two arrested and put the screws to them, they'll tell us all that themselves. Either way, they're the only ones who could have killed the maid. They're definitely the culprits. If we arrest them, there won't be any more murders.”

Kagami tucked in his chin and took a slow step forward. His sharp glare frightened Yuma into submission.

Even though he was a short, middle-aged man, he had a very solid, hefty body. He was probably stronger than Yuma. Moreover, as an active police detective, he must have had some knowledge of kendo and judo. It would be difficult to keep him from violently subjugating them. There was also the possibility that Sakyo and Sakaizumi would take his side.

If he was arrested here, his plan to uncover the identity of Oita's murderer and pin the blame for Kozushima's murder on them would be ruined. He and Kuruma would be arrested as dangerous criminals who had murdered three people.

What should he do? What should he do?

Frightened by Kagami's gradual approach, Yuma desperately racked his brains. His eyes landed on Tsukiyo, who was standing next to him.

That's right, he had an alibi. He was with her at the time both the second and third murders occurred. If only the great detective would support him...

Yuma and Tsukiyo's eyes met. A faint light returned to her hollow, clouded eyes.

Tsukiyo gave a gentle smile and nodded slightly, then turned to Kagami.

“The conclusion that Yuma and Mr. Kuruma are the culprits of Ms. Tomoe's murder is wrong.”

The stern voice echoed through the room. Kagami stopped where he was.

“Wrong? Then who killed those three?”

“I don't know that yet. But I can prove that the two of them didn't open the safe between when they put the master key inside in front of everyone and when they took it out just now.”

Yuma's eyes widened. He was sure she was about to mention his alibi. Why was she talking about the safe?

“Don't bullshit me. How could you possibly know that?”

Kagami sounded like he was threatening her. But Tsukiyo didn't back down.

“I'm not bluffing. I know, because I tampered with the safe.”

“Tampered?”

Kagami's nose crinkled.

“That's right. Yesterday, after the master key was locked away, I plucked a few of my hairs and stuck them in the gap of the safe's door so that they'd fall out if the safe was opened.”

Was that what she'd been doing when she checked that the safe door wouldn't open yesterday?

“And when I checked the safe before they opened it just now, the hairs were still firmly stuck in place. That means no one took the master key from the safe.”

“...That isn't evidence. You're the only one who saw it. You could just be lying to protect them.”

“I knew you'd say that. You're the archetypal stupid policeman in a mystery novel.”

Kagami's face flushed as Tsukiyo sneered at him.

“Then let me ask a question of you. Assuming Yuma and Mr. Kuruma were accomplices and used the master key to enter the Sixth room and kill Ms. Tomoe, why did they lock the door behind them?”

“Why...? Well, they must have locked it from the outside using the master key.”

“That isn't what I asked. I want to know why. If they were the culprits, there was no need for them to lock the room with the master key after leaving. After all, if they had just left the door unlocked, nobody would have suspected they'd used the master key.”

Kagami found himself at a loss for words.

“That's...”

“If the door hadn't been locked, we would have assumed that Ms. Tomoe had let the culprit into her room during the night. In that case, who would we suspect? The first person would surely be Mr. Sakaizumi, who was close to Ms. Tomoe.”

When his name suddenly came up, Sakaizumi looked up, tears still running down his face.

“Besides him, we may have also suspected Yumeyomi, who Ms. Tomoe may have felt safe around as a fellow woman, and Mr. Kagami, who would be trustworthy as a police officer.”

“I have nothing to do with it!” “Are you accusin' me!?”

Yumeyomi and Kagami shouted at the same time.

“Please calm down. I'm just discussing who we would have suspected if the room hadn't been locked. In other words, if the door hadn't been locked, Yuma and Mr. Kuruma would have been among the least suspicious people in the Tower. And yet you're saying they took the active step of locking the door with the master key? That doesn't make sense.”

Kagami couldn't argue with her explanation, and fell silent.

“On the other hand, it's possible that the culprit may have created this locked room through some other method in order to frame Yuma and Mr. Kuruma. At any rate, as things stand now, there is no basis for the conclusion that the two of them are the culprits. Do you understand?”

Tsukiyo's shoulders slumped as she let out a deep exhalation, as though she had found making another deduction exhausting.

“...I get it.”

Kagami sulked, turned back to the bed, took his smartphone from his pants pocket, and started taking pictures of Madoka's body.

“You all go back to your rooms, or the game room, or wherever. I'm documenting the scene.”

Kagami's voice was weak, as if being defeated by Tsukiyo had taken a great toll.

Yuma exchanged looks with Kuruma and the others. Even though they'd been told they could go anywhere they wanted, they didn't know what to do next. Tsukiyo, who had usually been the one to take initiative, was silent and downtrodden as the rest of them.

“Mr. Sakaizumi, are you alright?”

Sakyo called out to Sakaizumi, who was on the floor in a ball, trembling. Sakaizumi could only weakly shake his head.

Another victim had been claimed. Another body in a locked room. Yuma muttered to himself. He heard a clicking noise from somewhere. He didn't immediately realize it was coming from his own skull. His teeth were chattering.

“I can't take it anymore! Let me out! Get me out of here!”

Yumeyomi clawed at her pink-dyed hair with both hands. Sakaizumi's sobs grew louder. Sakyo looked around, face faltering. Kuruma dug his fingernails into his bald head.

Panic was spreading like a plague, infecting everyone it saw. Yuma desperately resisted the urge to join Yumeyomi in screaming and run away from the Tower.

“What's this!?”

Suddenly, Kagami cried out, drawing everyone's attention. Kagami's eyes were wide as he flipped up the bottom of Madoka's top.

Yuma and the others cautiously approached the bed. A groan escaped Yuma's throat when he saw the exposed white corset. Dark red letters had been scribbled there. Letters almost certainly written in blood.

All perspective vanished. The blood letters rose off the surface of the corset, and Yuma felt himself being drawn into them.

“Who is this Nakamura Seiji? Could it be that he's the murderer hiding in this tower!?”

Yuma looked at Yumeyomi, the one who'd asked. Then he met the eyes of Kuruma and Sakyo. Confusion was written across both their faces.

Nakamura Seiji? But... killing him...?

As Yuma, whose head was pounding from all the information being thrown at him, held his temples, Tsukiyo spoke softly.

“...The Bizarre House Murders.”

“Huh? Did you say something? Do you know this Nakamura Seiji guy?”

“Yes, of course.”

Tsukiyo nodded listlessly.

“Nakamura Seiji was an architect, born in Oita Prefecture on May 5th, 1939. He became famous for designing many strange mansions.”

“He was born before the war? He must be pretty old. Why is his name here...?”

Kagami said that, then his eyes shot open.

“You said he designed strange mansions. Do you mean he designed this building, too? Is this blood lettering saying to kill the man who designed this Tower!?”

“No, that isn't it. Nakamura Seiji isn't real.”

“What? What are you talking about? You just said you knew him!”

Kagami turned on Tsukiyo. Yuma hurriedly stepped between them.

“Please calm down. Nakamura Seiji is a fictional character.”

“A fictional character?”

Kagami asked with suspicion, and Yuma nodded. Anyone with even the slightest knowledge of Japanese mystery should have recognized the name. He was the designer of the legendary mansions, a character from the masterpiece that sparked the shin honkaku movement.

“Nakamura Seiji is the name of a character who appears in The Bizarre House Murders, a series of honkaku mystery novels written by Ayatsuji Yukito. The basic premise of The Bizarre House Murders is that a series of murders takes place in the strange buildings designed by Nakamura Seiji, and the protagonist, Shimada Kiyoshi, travels to each house and solves their mysteries.”

“Another mystery novel!? Enough already. Three people have been killed! Why would a fictional character's name be written in blood on the corpse!? And it says to kill him. What, are we going to kill the guy from the books!?”

Ignoring Kagami, who was stomping his feet with anger, Tsukiyo turned on her heel and left.

“Hey, where do you think you're going?”

“I'm off to kill Nakamura Seiji.”

Tsukiyo answered in monotone, then left the room and went down the stairs.

“Wait a second, what do you mean you're going to kill him?”

Kagami ran after Tsukiyo and disappeared. Yuma and the others followed, locking the Sixth room behind them with the master key before descending the stairs.

Arriving on the first floor, Tsukiyo walked down the hall without looking back. Her steps sounded extremely heavy. She reached the double doors to the theater, opened them, and went inside.

In the dimly lit theater, Tsukiyo reached the screen showing the blue mansion, turned around, and held out a hand to Kagami, who had followed her in.

“Please lend me your lighter. You must have one, you're a smoker.”

“...How did you know I smoke?”

“The smell. The smell of cigarettes thoroughly permeates the bodies of heavy smokers. And I need a lighter to explain the meaning of the bloody letters on Ms. Tomoe's corset. Or do you not want to know that?”

Kagami put a hand into the pocket of his suit with a grim expression and took out a Zippo lighter.

Tsukiyo took the lighter, which was marked with the image of a parabola, and opened it with practiced hands before bringing it up to the screen. Yuma gasped. Kagami's eyes went wide and he shouted “Hey, wait! Don't!” But Tsukiyo lit the flame without hesitation. The flames spread across the screen.

As Yuma and the others stood speechless, Tsukiyo stared coldly as the image of the blue Western-style mansion was engulfed in flames that turned her face orange.

“What are you doing!? What if you start a fire?”

“It's fine. There's nothing flammable near the screen. The fire won't spread.”

Tsukiyo spoke lifelessly without even sparing a glance at Kagami. True to her words, the fire burned out without scorching the walls or ceiling. Tsukiyo's expression never changed, even as the screen was consumed in flames before her eyes.

Yuma's eyes widened when he saw what was on the other side of the screen. There was a space about a meter deep, and on the floor was some sort of metal lid. Tsukiyo approached the lid and grabbed the rusty handle with both hands. When the lid was raised, a staircase descending underground was revealed.

“Stairs? Do they lead to the underground storeroom?”

Kagami muttered to himself. Tsukiyo listlessly shook her head.

“No, they don't. Judging from their position, there isn't supposed to be anything below here. In other words, this is a staircase to a secret basement. The one who killed Ms. Tomoe left those words in blood on her corset so we would find it.”

Tsukiyo climbed over the still burning remnants of the screen and tried to descend the stairs, but Kagami grabbed her by the shoulder.

“Hold up. How did you know about these stairs just from the blood letters? Explain.”

“...We've already found the secret basement. It doesn't matter how.”

“That won't fly here. If you don't explain, I might start thinking you wrote that yourself. You wrote something that looked kinda like a code, pretended to 'solve' it, then brought us here.”

“Why are you being so difficult? Fine, I'll explain.”

Tsukiyo began to speak, looking exhausted.

“As Yuma said earlier, Nakamura Seiji is an architect who appears as a character in Ayatsuji Yukito's Bizarre House Murders series. And Mr. Kozushima, a mystery fan, had a particular fondness for The Bizarre House Murders, especially The Decagon House Murders, which sparked the shin honkaku movement.”

Tsukiyo scratched the tip of her nose.

“I can understand Mr. Kozushima's feeling well. The Decagon House Murders represents a major milestone in the world of Japanese mystery novels. It inspired the success of many outstanding talents, like Norizuki Rintaro, Arisugawa Alice, and Abiko Takemaru, and caused the popularity of honkaku mysteries, which had been steadily declining since Matsumoto Seicho achieved popularity, to explode into the shin honkaku movement.”

As Tsukiyo's voice refilled with passion, Kagami scowled.

“But Shimada Soji is really the one who planted the seeds of the shin honkaku movement flowered by The Decagon House Murders. His debut, The Tokyo Zodiac Murders, published in 1981, captivated many fans of honkaku mystery. Among them was Ayatsuji Yukito. Shimada Soji himself wrote many other masterpieces like Murder in the Crooked House and The Man-Eating Tree on Darkness Hill while also introducing the world to many young writers who would go on to lead the shin honkaku movement, like Ayatsuji Yukito, Norizuki Rintaro, and Utano Shogo. Without Shimada Soji, The Decagon House Murders would have never been written, and the shin honkaku movement never would have happened. Of course, there were also authors like Ayukawa Tetsuya who supported honkaku during the era when it wasn't popular-”

“Stop talking nonsense. Just get to the conclusion!”

Unable to take it any longer, Kagami interrupted in a raspy voice. Tsukiyo blinked.

“Conclusion? Do you want to know my favorite book in The Bizarre House Murders series? It's The Clock House Murders-”

“Tell me how you knew about the stairs!”

“Right, that's what we were talking about.”

Tsukiyo's voice instantly died.

“In short, Mr. Kozushima was inspired by The Bizarre House Murders when he built this Glass Tower. And the home of Nakamura Seiji, the one who designed all the bizarre houses that serve as the series's settings, was...”

“The Blue Mansion!”

Tsukiyo turned to Yuma, who had blurted out the answer, and said with a weak smile

“That's right, Yuma.”

“What's the Blue Mansion?”

Kagami asked, redirecting his anger at Yuma.

“It was the home where Nakamura Seiji himself lived, which was built on the island of Tsunojima. The Decagon House, the titular setting of the first book, The Decagon House Murders, served as its annex. However, in the story, the Blue Mansion was burned down, and Nakamura Seiji's corpse was found burned to death in the ruins.”

As Yuma explained, Kagami turned his gaze back to Tsukiyo.

“A burnt body... so that means...”

“Yes. The words 'KILL NAKAMURA SEIJI' written in blood on the corset were instructions to burn this screen. The killer must have tortured Ms. Tomoe to find the location of this place. Then they left a message in blood to lead us here.”

“You really think the culprit expected us to get all that just from the words 'KILL NAKAMURA SEIJI'?”

Kagami asked, nakedly skeptical.

“The Decagon House Murders is one of the most famous mystery novels in Japanese history, and the fate of Nakamura Seiji and the Blue Mansion is revealed extremely early on. Even outside of Japan, The Decagon House Murders was first translated into English all the way back in 2015, and even the manga adaptation began official translation in August 2021. Then in 2024, it was adapted into a live action drama as well. What I'm saying is that it's an extremely accessible story all over the world, and frankly, any so-called mystery fan who didn't make the connection should be ashamed of themself-”

“I get it.”

Kagami was completely done with the great detective's eccentricities.

“What's at the bottom of those stairs!?”

In response to Yumeyomi's question, Tsukiyo weakly replied “I'd like to know that myself,” and started down the stairs with zero hesitation. Yuma and the others hurried after her.

They made their way down a narrow, dimly lit set of stone stairs. Their footsteps echoed loudly off the walls. A bare light bulb hung from the low ceiling, easily within reach.

“It looks like some sort of medieval dungeon.”

Yuma remarked to nobody in particular, but Tsukiyo, who had been walking ahead of him, turned back and quirked her lips in a sly grin.

“A dungeon, is it? You might not be far off the mark, Yuma.”

“What do you mean?”

Tsukiyo didn't respond, just turning back and continuing down the stairs.

After a few dozen seconds of careful descent, they arrived in a dark space. From the light coming from the bare bulb over the stairs, they could tell that a dark cobblestone corridor stretched out before them, but the deep darkness filling the space beyond prevented them from seeing anything more.

“Ah, there's a switch here.”

Kuruma pressed the switch embedded in the stone wall. LED lights embedded in the gaps between the stones lit up. The faint orange light filled the darkened corridor, like the emergency lights illuminating a runway.

“A dungeon...”

Sakyo's voice was a rasp. Just as he'd said, the corridor had iron barred doors, three on either side.

“I told you, Yuma. You were right.”

Tsukiyo stared unblinking down the corridor.

“Did you know that there was a dungeon here?”

“I didn't know. But given the information we had, I made an educated guess.”

Tsukiyo walked down the corridor. The sound of her leather shoes on the stone floor echoed down the hall.

Yuma followed behind her and peered through the bars of one of the cells. Beyond was a space of about eight square meters, containing only a toilet and a simple bed. Broken cups and a large dog bowl lay on the exposed concrete floor.

There was no light within the cell, so it was hard to see. Yuma squinted. As his eyes adapted to the dark, he saw “something” on the bed in the back of the room. He suddenly clapped both hands over his mouth, overcome by an intense need to vomit.

It was a corpse. A nearly skeletal body dressed in a mountaineer's outfit. There was almost no flesh left on the hands and face emerging from the woman's clothes, and hollow eye sockets seemed to stare right at him.

“W-What the hell is this!?”

Yumeyomi collapsed on the spot, screaming. Her back hit the iron bars of the opposite cell. As she turned around, a hideous, piercing shriek roared from her mouth.

In the bed of the other cell was another skeletal body in mountain climbing gear. Judging from the clothes, this one was probably a man.

“Please don't be so loud. It's a corpse. Judging from the state, it has probably been dead for a long time.”

Tsukiyo covered her sore ears.

“Ms. Aoi, what is this place? Who are these people? If you know, please tell us. I don't know what's going on anymore...”

Kuruma was breathing heavily.

“As you can see, it's a dungeon. And these bodies probably belong to the victims of the Chogatake Spiriting Away incident.”

“The Chogatake Spiriting Away incident...”

“Yes, that's right. Those climbers didn't just get lost. The victims who strayed from the proper route arrived here in the Glass Tower, where they asked for help. But they were kidnapped by Mr. Kozushima and his henchmen and imprisoned in this dungeon.”

Suddenly, Kagami ran up to the far rear of the cells on the right and grabbed the bars. His facial muscles tensed so hard they exposed his clenched teeth.

“Damn it... damn it...” he cried.

“What is it, Mr. Kagami?”

Yuma asked hesitantly, and Kagami pointed a trembling finger at the back of the cell. Just like in the others, a skeleton in mountain climbing gear was lying there.

“That's what Mashu Shinju was wearing the day she went missing. That's... Mashu Shinju's body.”

“Mashu Shinju was the name of the missing woman you were searching for, wasn't it?”

“That's right. I was too late...”

Kagami bit his thick lip nearly hard enough to draw blood. He was an arrogant man, but it was clear that the regret that he had failed to save the woman was destroying him inside.

“It's locked, I can't open it. Unfortunately, it doesn't look like we can investigate the insides of the cells in detail.”

As Tsukiyo muttered to herself, gazing at the iron bars, Sakaizumi spoke up.

“Um... This cell is unlocked...”

Sakaizumi limply pointed to the cell in the rear to the left. He appeared to no longer be in shock from Madoka's death, but he still looked exhausted and lifeless.

Yuma turned and looked at the cell. Sure enough, the door was open, and there was no body inside.

“Maybe nobody was locked inside to begin with,” said Sakaizumi.

“Or maybe they escaped,” Tsukiyo replied.

Someone had escaped from that cell and was hiding somewhere. The atmosphere instantly tensed.

“So, like you theorized yesterday, either Mr. Kozushima or Mr. Oita was Fuyuki Daisuke, the culprit of the Chogatake Spiriting Away incident, and they've been committing crimes ever since?”

Kuruma's voice was tense.

“It isn't fully proven, but I think we can say it's much more likely then not.”

Tsukiyo stood before the iron double doors at the end of the corridor and pushed them with both hands. Yuma couldn't believe what lay within. The pale glow of fluorescent lights exposed a laboratory. A large laboratory about the size of a basketball court.

Large cabinets of equipment, a centrifuge, a microscope, an ultra-low temperature refrigerator... there was even an operating table.

“The hardest part was taking care of the test subject animals. They would yell so loudly, they were hard to feed, and they would get violent during the experiments.”

Tsukiyo recited like a bad actress. On the first day, when Kuruma had asked about Kozushima's research, Madoka had answered him.

“You mean the animals...”

The deathly pale Kuruma could barely speak.

“Yes, they were likely mountaineers who had been abducted after getting lost. Mr. Kozushima was a man who wanted, above all, to be famous. He wanted to make a name for himself in the field he loved, mystery fiction, but I think he understood that he had a better chance of succeeding in the field of science he specialized in.”

“But Mr. Kozushima had already achieved wealth and fame with the TRIDENT.”

Yuma argued, but Tsukiyo barely spared him a glance.

“Yuma, human desires aren't something that can ever be fulfilled. The more famous a person is, the faster they grow dissatisfied. They crave more and more praise. It's like sinking into a bottomless swamp. Someone like Mr. Kozushima wouldn't have been choosy about his methods, even if it violated all sense of ethics.”

Tsukiyo entered the lab.

“It is true that ethics impede the development of science. Experiments on stem cells made from fertilized eggs were banned on the grounds of bioethics, stalling regenerative medicine for years until the invention of induced pluripotent stem cells. Scientists who ignore ethics are like athletes who use steroids. They can make rapid progress in their field.”

It was the Nazis who made the greatest advances in medical science in the shortest amount of time.

The words Kozushima had spoken just before Yuma poisoned him flashed through Yuma's mind. He felt like ice water had been poured directly into his spinal cord.

“So Mr. Kozushima was using the victims to perform human experimentation?”

“That's most likely it.”

Tsukiyo ran a finger over the table beside her. Her fingertip came back white with dust.

“But the fact that the laboratory is covered with this much dust would suggest that plan was thwarted quite some time ago. No matter how expensive the research facility, advanced science requires manpower. Amateurs like Mr. Oita and Ms. Tomoe could perform odd jobs, but they couldn't actually help with the research. But there's no way Mr. Kozushima could go around hiring for an illegal human experimentation position. And so, Mr. Kozushima once again gave up on achieving any further fame in the field of science and focused on leaving in impact in the field of mystery. Judging from the thickness of this dust, that must have been about a year ago. Ms. Tomoe also said that was when Mr. Kozushima stopped his research.”

“Hold on a second.”

Kuruma spoke up.

“You say the research was stopped, but what happened to the people locked in this dungeon?”

“I believe it's most likely they were abandoned at the same time as the laboratory.”

“Abandoned...”

“Yes. Mr. Kozushima decided not to continue his research, so he locked his victims in the dungeon and abandoned the whole facility. He couldn't let them leave, but killing them would be too much work. It would be the least hassle for him to do nothing.”

“But if he just left them here...”

“They starved to death, of course.”

Tsukiyo locked eyes with the speechless Kuruma and explained calmly.

“Here in the darkness, ravaged by thirst and hunger, the victims must have silently lay in their beds, praying that saving their strength would allow them to survive just a moment longer. They believed that help would come someday. But their wishes went unanswered, and one by one, trapped in despair, they lost their lives. Their bodies rotted away, and in the end, nothing of them was left but their bones.”

Tsukiyo stopped and looked around at everyone present. A heavy silence filled the laboratory.

“So this present case...”

Kuruma finally broke the silence. Tsukiyo gave a vigorous nod.

“Yes, the motive was revenge. Someone close to one of the victims who died in this dungeon killed the three people involved in the inhuman research. First, they poisoned the ringleader, Mr. Kozushima, then killed Mr. Oita, leaving the words 'SPIRITED AWAY FROM CHOGATAKE' in blood at the scene to explain why they committed the crime. Finally, they tortured Ms. Tomoe into telling them the location of this laboratory, then killed her, leading us here with the bloody writing on her corset.”

“Why did they want to show us this place?”

“I think they wanted to show us their actions were just. They didn't kill for their own selfish gain, but dealt a fair punishment to those who had strayed from the path of humanity. That also matches with the fact that they left information on their motive at the scene of Mr. Oita's murder.”

“...A fair punishment?”

Kagami, who hadn't spoken since finding the body that supposedly belonged to Mashu Shinju, spoke in a low, dangerous voice.

“'A fair punishment' is what it's called when the police make an arrest, prosecute the culprit, and give them a sentence. When civilians get their own hands dirty, it puts them on the same path as the people they've killed.”

“But the police didn't even believe that Mashu Shinju was the victim of a crime until you saw this dungeon. I mean, that's what you said, isn't it, Mr. Kagami? I'm sure the culprit resorted to this because they felt they couldn't rely on the police.”

Kagami scowled, but said nothing. Instead, it was Yumeyomi who started talking.

“Wait a minute. What about the empty cell? Maybe the person in there took revenge.”

“It's possible,” Tsukiyo stroked her chin. “But I don't think it's very likely, considering how long its been since this place was abandoned.”

“No, I'm sure it was them. The evil presence I've felt all this time was that person. They've been lurking in the Tower all this time, waiting for their chance to kill those three.”

“So the culprit is a vengeful demon who has been living down in this darkness for over a year?”

Tsukiyo said “That's an interesting hypothesis,” but her expression was dour.

“Ms. Aoi, do you know who the culprit is yet? Do you have any idea how they killed those three people in locked rooms?”

Kuruma stepped forward. Tsukiyo slowly shook her head.

“No, I don't know that yet. However, there is something more important than the culprit's identity or the locked rooms.”

“Something more important than the culprit's identity?”

“If the motive was revenge, that means it's unlikely there will be any more murders.”

As everyone let out various noises of surprise, Tsukiyo straightened her back.

“The only people who lived in the Glass Tower were Mr. Kozushima, Mr. Oita, and Ms. Tomoe. It's unlikely anyone else was involved in those devil's experiments. The moment they killed the three of them and revealed this secret basement to us, the culprit achieved their goals. That means there won't be any more victims. We just have to wait until the police arrive tomorrow.”

“Yeah, that's right,” Kagami said in a low voice. “Just leave the rest to us. Once forensics gets here, we can do a thorough investigation and find everything the culprit left behind. And if the motive was revenge, it'll be easy. We'll just do thorough background checks on all of you and find out who's related to one of the dead bodies in those cells. Then we'll book 'em.”

That wasn't good. Yuma swallowed the lump in his throat. If the police did their investigation, they would learn about his sister and realize that he had a motive to kill Kozushima. Even if they did manage to find out who killed Oita and Madoka, they would probably tell the police they weren't the one to kill Kozushima.

He had to find out who'd killed Oita and Madoka before tomorrow evening and produce evidence that they'd also killed Kozushima. But how...?

As Yuma's brain raced for an answer, Sakyo spoke up.

“So, what should we do now...?”

“I don't think it would be good to completely lower our guards. We should either all stay in our rooms like we did yesterday, or publicly announce our locations.”

“Then... I think I'll go back to the game room with Mr. Kuruma. Is that alright with you, sir?”

“I'm alright with that. If it's just until tomorrow, I can probably stay awake. If possible, I'd like to stay in the game room non-stop until the police arrive. Does that work for you, Sakyo?”

“Yes, I'd like that as well. Since Ms. Tomoe was killed in her room, I'm a bit uneasy staying in my room alone. Um, is there anyone else who would like to spend the night in the game room?”

When Sakyo asked, Sakaizumi weakly raised his hand and said

“Is it okay if I stay with you?”

“Of course. After all, it's safer in a larger group.”

“No... I'm not worried for my safety. I just don't think I could stand to be alone right now. I still can't believe Madoka's dead. And she was involved in something so horrible...”

Sakaizumi covered his face with both hands and began to gently convulse. Kuruma placed a hand on his back.

“Then Sakyo, Sakaizumi, and I will stay in the game room. Will anyone else be joining us?”

“Sorry, but no!” Yumeyomi spat. “Even if they aren't targeting me, I don't want to hang out with men who could be serial killers. I'm going back to my room, and I'm not leaving until the police arrive.”

“But Ms. Tomoe was killed in her room. Locking the door might not deter the killer.”

Sakyo said, but Yumeyomi waved a hand at him and said

“Oh, shut up. I'll just barricade the door with some furniture. I'm going to my room.”

“I'll stay in my room, too. There's no reason anyone'd want me dead.”

Kagami had also declared he would stay in his room. Kuruma turned to Tsukiyo and Yuma.

“What about you two?”

What should he do? What would bring him closer to finding Oita and Madoka's killer? Before Yuma could decide on an answer, Tsukiyo turned to him.

“I'm going to rest in my room. Yuma, you're going back to your room too, aren't you?”

Yuma stared at Tsukiyo and said

“Ah, yeah...”

“Alright, let's all go. For now, everyone be careful.”

Kuruma spoke hesitantly, and Kagami pointed at Sakaizumi and said

“Wait a minute. First, we need to put the master key back in the safe. If someone with a master key is wandering around, no one will feel safe.”

“Yeah, you're right. Let's go to the storeroom first.”

At Kuruma's signal, everyone walked with heavy steps. Sakaizumi was particularly unsteady, looking like he would collapse at any moment.

After they'd left the dungeon and returned to the first floor, Yuma and the others descended the spiral staircase to the underground storeroom.

“C'mon, put the key in already.”

At Kagami's urging, Sakaizumi unsteadily approached the open safe and went to crouch down. At that moment, his body dramatically swayed over. Just as he was about to fall, Tsukiyo quickly moved to catch him and hold him up.

“Are you okay, Mr. Sakaizumi?”

Tsukiyo's smile would have been an obvious fake even to someone who didn't know her. It looked like she was desperately clinging to her pride as a great detective, even as it prepared to crumble away at any moment.

“I'm okay. Sorry.”

After regaining his balance, Sakaizumi placed the master key in the safe, and Kagami forcefully shut the door.

“Come on, you two, lock it up.”

Kagami jerked his chin. Yuma and Kuruma used their keys to lock the safe.

“We should be safe now,” Kuruma said as he took the key from the lock and returned it to his pocket.

“No, not yet.”

As soon as he said that, Kagami turned the combination lock. Yuma's eyes widened.

“What are you doing!? Only Mr. Kozushima knew the combination!”

“So?”

Kagami eyed him coldly.

“So? So if something happens now, we can't get the master key!”

“Again: So?”

Yuma went “Huh?”

“What are you afraid of? The three people who killed all those skeletons in the basement are dead. Just like the great detective said, the perp's revenge is over. If you think there's somethin' else...”

Kagami passed by Yuma as he stood there at a loss for words. Their shoulders roughly pressed against each other.

“The police will be here tomorrow. All we have to do is wait. So, for the sake of the people who are going to spend that time holed up in their rooms, it's better if no one can access the master key. The possibility that 'a certain someone' killed the maid with the master key still hasn't been ruled out.”

Without turning back, Kagami grabbed some preserved food off the shelf, stuffing it in his suit pockets as he disappeared up the stairs. He probably planned to stay in his room until the police arrived.

“...I'm sorry, but everyone going back to their rooms, please take whatever food you need from here. I don't think I can cook anymore.”

Sakaizumi spoke quietly. Hearing him, Yumeyomi grabbed two heaping armfuls of food and ran from the storeroom.

“Well, shall we get going?” Kuruma asked. Everyone else also went to leave.

As they made their way for the stairs, Yuma grabbed a few biscuits and put them in his jacket pocket. He had no appetite, but he needed to get something in his stomach. There was still a day and a half until the police arrived, and he had to find out who had killed Oita and Madoka.

No one except Yuma reached for the food. The group climbed the spiral stairs in silence. When they reached the first floor, Kuruma said “Well, here we are,” and entered the game room with Sakyo and Sakaizumi. Yuma and Tsukiyo continued going up the stairs.

Yuma had to talk to Tsukiyo, who was walking ahead of him with her head down. He needed her help to uncover the identity of the culprit who'd killed Oita and Madoka. But for some reason, Tsukiyo had fallen into a depression and completely lost her great detective's spirit, so he had no idea what to say to her.

The two of them silently arrived at the Fifth room. Tsukiyo used her key to unlock the door and opened it.

Yuma said “Um...” Tsukiyo turned around and met his eyes, and the words on his tongue melted away. The eyes that gazed back at Yuma were impossibly dark and deep as a bottomless swamp. Yuma was trapped by the illusion the eyes were sucking him in.

What harsh experiences did a person have to go through to fill their eyes with such darkness?

Tsukiyo looked away from Yuma, who stood mesmerized, and disappeared through the door. There was the heavy sound of the door closing, followed by the lighter sound of the lock. To Yuma it sounded like their relationship as detective and Watson being snapped in two.

Perhaps Tsukiyo had given up on being a great detective. With that premonition in mind, Yuma dragged his feet as though they'd been shackled all the way back to the Fourth room.

Yuma entered the room, locked the door behind him, and collapsed into bed.

What should he do now? He thought as he gazed at the ceiling. Judging from what he'd seen earlier, he couldn't rely on Tsukiyo any more. For some reason, Madoka's case had shocked her to the point where she could no longer function as a great detective. If he couldn't rely on her, the only option left was to find the culprit of Oita and Madoka's murders himself. Yuma frantically wracked his brains.

Under the circumstances, the case was most likely a revenge killing carried out by someone close to one of the victims in the underground dungeon. However, trapped as he was in the Glass Tower, it would be impossible for him to find out who any of those bodies were, let alone who was close to them, before tomorrow evening.

If there was no way to find the motive, the only other path was to nail the culprit with evidence.

Having gotten that far, Yuma grit his teeth.

How had they locked the dining room and started a fire from the inside? How had they gotten into the Sixth room and locked the door from the outside while the master key was kept in the safe? If he could solve the locked room tricks, he may have been able to identify the culprit. That was what he thought, but he didn't have a single clue to the truth.

A dull pain formed in his eyes. His thoughts were growing hazy. His nerves had been on edge for two days straight, and he'd barely slept. The abnormal situation had left him both physically and mentally exhausted. His eyelids were so heavy...

Yuma slowly closed his eyes. Just a moment. He would just take a short nap. That would help his brain to recharge and confront the mystery properly. His consciousness sank into the darkness. At that moment, a knock filled the room. Yuma's eyes shot open and he jumped out of bed.

Who was there? The image of Madoka lying in her bed, clad in that damp red wedding dress, filled his mind. Had the culprit come to kill him as well?

Yuma cautiously approached the door and asked

“Who is it?”

“It's me, Yuma.”

Tsukiyo's voice came through the door. Yuma's tension didn't dissipate.

Could Tsukiyo have been the one to kill Oita and Madoka? She was a total mystery freak, so she could have staged an incident like one from a honkaku mystery novel... Realizing what he was thinking, Yuma's lips curved in a self-deprecating smile.

Was he an idiot? They had been together during both the second and third cases. There was no way she was the culprit.

“Can you open the door, Yuma?”

“Just a moment.”

Yuma hurriedly unlocked the door and opened it.

“Thank you. May I come in?”

Tsukiyo looked at him. She looked like a lost child. Her tall figure now looked awfully small.

“Of course.”

Yuma invited her in, and Tsukiyo slowly approached the couch and sat down.

“What is it all of a sudden?”

Yuma locked the door and sat down across from her.

“Am I bothering you?”

“No, that isn't it... I'm just worried because you looked so depressed earlier.”

“Depressed... Yes, I suppose I am. That's why I came. It's your job as my Watson to comfort the great detective when she's feeling down.”

“Comfort...”

“Oh, don't get me wrong. I don't mean 'comfort' in a sexual sense. I have no intention of becoming romantically entangled with my partner. I just want you to comfort me as a friend.”

“I know that much,” Yuma frowned.

“I'm relieved that you're such a gentleman, Yuma. You see, in The Tokyo Zodiac Murders, Ishioka comforted Mitarai Kiyoshi when he fell into a depression over his inability to find the truth of the case, and inspired him to solve that legendary trick. I remembered that and decided to come visit you.”

“Even if you tell me that... Why are you so depressed, Ms. Aoi?”

“...Because I'm disappointed.”

“Disappointed? About what?”

Tsukiyo looked into the air, searching for the words.

“I suppose it's because I'm a great detective.”

“Because you're a great detective?”

When Yuma asked, Tsukiyo solemnly lowered her eyes.

“Yes. The concept of 'a great detective' is full of contradictions. Yuma, what does 'great detective' mean to you?”

Yuma thought on the question for a few seconds before answering.

“Someone who can solve any case no matter how difficult, I suppose.”

“Exactly. Great detectives solve cases. There are many different motives and methods, but in the end, the definition of 'great detective' is 'someone who solves mysterious crimes that even the police can't handle'. But what is that worth?”

“It's worth plenty. You can arrest criminals who would otherwise go free.”

“You're right, of course. But what about the victims?”

“The victims...”

Yuma repeated.

“For the victims who have already been murdered, it doesn't matter whether or not the culprit goes free.”

“That isn't true. Exposing the culprit and having them punished helps to put the victims to rest.”

“Put the victims to rest, huh?”

Tsukiyo's smile didn't reach her eyes.

“You're quite the romantic, Yuma. You believe that souls remain even after death.”

“No, it's not that I particularly believe in souls...”

“Well, let's not discuss that now. Do people continue to exist after death? Is there an afterlife? They're interesting questions, but not the sort of thing we should be discussing under the circumstances. But if there are such things as souls, I don't think they would tell great detectives 'Have the culprit punished.” I think they'd be too busy asking 'Why didn't you save me?'”

“You're overthinking things. No matter how great a detective you are, you can't act unless a crime has been committed.”

“Inoue Magi's The Detective is Too Fast features a detective who prevents crimes from being committed.”

Tsukiyo raised her lips in a lifeless grin.

“That's different. In reality, things don't work out that neatly. There's no need to worry about that.”

“You're very kind, Yuma. But I think even great detectives who brilliantly solve the most incredible cases are actually weak, passive beings. All they can do is wait for someone else to commit a case that allows them to make use of their skills.”

“That's... inevitable. Even if you can't prevent crimes, you're still a great detective. There's no contradiction there.”

“Oh, I'm sorry, was I not clear? That isn't what I'm depressed about. I've already come to terms with that. The contradiction I was talking about is about the reputation of a great detective and the scale of the case.”

“The scale of the case?” Yuma repeated.

“Which is a more suitable case for a great detective: a case with one victim, or a serial killing with many victims?”

“...The serial murder,” Yuma replied softly, instantly understanding what Tsukiyo was getting at.

“Yes, a complicated, bizarre serial murder case where many victims are brutally killed one after another is the ideal stage for a great detective. Solving a case like that will bring recognition as a great detective. But conversely, it will mean they failed to prevent the serial killing.”

Tsukiyo looked up at the ceiling and gave a deep sigh.

“Fail to prevent the crime, allow the number of victims to increase beyond reason, and then after it's all over, you gather everyone and proudly denounce the culprit. Is that really okay? The ideal result would be to identify the culprit after the first murder and prevent the rest of the crimes. But in reality, it's the former that makes you a great detective. That contradiction has been bothering me for a long time.”

“...Is that why you were so depressed? Are you upset with yourself because you couldn't prevent Ms. Tomoe from being killed?”

Yuma whispered the question under his breath. They couldn't conclusively determine whether or not Kozushima's death was a murder, but the scene where Oita was found was obviously a murder no matter how you looked at it. Therefore, as a great detective, she should have uncovered the culprit's identity quickly and prevented further harm.

Tsukiyo's only reply was a smile. It was a fleeting smile that looked like it was made of glass, like it would break under the slightest touch.

“Ms. Aoi...”

Yuma looked into Tsukiyo's eyes. Their gazes intertwined.

“Why do you want to be a great detective?”

Aoi blinked several times, then gave a small shrug.

“I can tell you, but are you sure? It's a long, boring story.”

“That's fine. If you give up being a detective due to this case, all we'll have left is to wait until the police arrive tomorrow. We'll have plenty of time for long, boring stories.”

“Hmm, I suppose you're right. It isn't really the sort of thing I like sharing, but I guess I should at least tell my Watson.”

Tsukiyo's eyes wandered to the ceiling. She could only have been looking at her memories of the past.

“I didn't really realize it myself, but apparently I was a very unique child, and I never really fit in with those around me.”

So nothing's changed then, Yuma thought to himself as he nodded along.

“Humans are cruel creatures. They instinctively try to eliminate anything that's different.”

“Were you bullied as a child?”

“Bullying... I suppose you could call it that. But to my child self, it was nothing less than persecution. A rejection of my very existence.”

Perhaps remembering that time, a dark shadow fell across Tsukiyo's face.

“But I was lucky. My family was quite wealthy, so I had an escape: my room. I spent most of each day holed away in there.”

She had been severely bullied in school, and became a shut-in. Yuma continued listening in silence.

“Another point where I got lucky is that my father was quite the fan of mystery fiction. There were more mystery novels in our home library than I could read.”

“You're just like your father.”

“Yes, I suppose I am.”

Tsukiyo's eyes narrowed with nostalgia.

“Poe, Leblanc, Doyle, Christie, Queen, Carr, Rampo, Yokomizo, Ayukawa, Shimada, Ayatsuji... From foreign classics to the shin honkaku movement, I became engrossed in reading my way through my father's collection. For me, who felt the world was rejecting me, the world of mysteries was nothing less than a utopia. Dazzling, fascinating mysteries are presented, and a great detective dashingly sweeps in and solves them with a flourish. I became absorbed in such stories, and as I became more and more absorbed in them, the line between fiction and reality began to blur. Holmes, Dupin, Queen, Poirot, Akechi, Kindaichi, Mitarai. I believed without a doubt that those great detectives were real, and they could easily solve any tragedy.”

“That's a bit much...”

Yuma gave a strained smile, and Tsukiyo shrugged.

“I suppose I wasn't normal, then?”

“No, that isn't what I meant...”

Yuma hesitated, and Tsukiyo shook her head and said

“It's fine. I may have actually been an abnormal child. But if I can make an excuse, I don't think that could be helped. I averted my eyes from a painful reality, and began to live within a fantasy world to protect my mind. It's a common defense mechanism for children in harsh environments. I believed in great detectives, and by working with them to solve cases, I was able to preserve my sense of self.”

Tsukiyo looked off into the distance.

“To me, great detectives were heroes who would always help me.”

“So you wanted to become someone like your heroes?”

“No, it isn't such a happy story.”

The expression faded from Tsukiyo's face like a receding tide. Yuma stiffened as the temperature in the room suddenly fell. Tsukiyo moistened her lips before speaking quietly.

“Exactly ten years ago, when I was in high school, there was an incident.”

“An incident...?”

Yuma's mouth was dry, and his voice cracked. Tsukiyo slowly lowered her head.

“My parents were murdered. It was a case directly out of a mystery novel.”

Tsukiyo kept her eyes locked on the speechless Yuma and continued calmly.

“That morning, my parents didn't wake up, so I knocked on the door of their bedroom on the third floor, but there was no response. Suddenly, I felt something slimy on my toes, and when I looked down, my slippers were wet with a red liquid. A dark red liquid was oozing from the gap under the door.”

Overwhelmed by Tsukiyo's voice, impossible to read, Yuma sat and listened in silence.

“I immediately called the police, and they rushed to the scene. They kicked down the locked door, and they all screamed at the nightmarish sight within. One of them vomited on the spot. It was horrifying.”

“What happened to your parents...?”

“My father and mother were dead, sitting next to each other on the bed. In their laps, they were holding each others' severed heads.”

Tsukiyo frowned as if enduring a deep pain.

“When the police investigated the scene, they determined that the two of them had been stabbed once each in the chest with a sharp blade in the middle of the night, and then decapitated posthumously. The door to the room was locked, and the only key was found on my father's desk. The crescent lock on the only window was also down.”

“That means...”

“Yes, it was a locked room murder. A wealthy couple was found dead in a locked room, holding each others' severed heads. It's exactly the sort of case you'd expect to find in a honkaku mystery story.”

The sight of Tsukiyo playfully stretching out her arms was so painful that Yuma had to avert his eyes.

“...And then what happened?”

“What happened? Nothing. Nothing happened.”

A self-deprecating smile covered Tsukiyo's handsome face.

“I assumed a great detective would come from somewhere and expose the one who'd murdered my parents. I was convinced of that. But no matter how long I waited, that great detective never appeared. An investigation headquarters was established and the police investigated as much as they could, but time passed without anyone ever learning how the culprit created the locked room.”

“Do you have any idea who the culprit is?”

“There seem to have been a few suspects. My father had made a few enemies due to his business. But they were never able to identify the culprit. Eventually, the investigation headquarters was disbanded, and the investigation was scaled down until the case went unsolved. So I personally asked various detectives to investigate instead. I'd inherited my father's fortune, so I had plenty of money.”

“And did you make any progress?”

“Absolutely none. The detectives I hired were all specialists in things like infidelity investigations, so they weren't of much use in a criminal case. Unfortunately, the sort of hero I was waiting for didn't exist in reality. The case is still unsolved. The one who killed my parents is still out there.”

Tsukiyo waved her hand dismissively.

“I was disappointed. I was truly, deeply disappointed. My world was one where great detectives existed. And then, I'd been confronted with an absence of great detectives. My world was silently shattered. I felt like the ground had crumbled beneath my feet and I'd been cast into an endless void. For the next several months, I lived like an empty shell. I breathed, I ate and drank the bare minimum necessary to survive, I used the bathroom, and I slept. I was a living corpse. But one day in that waking nightmare, a revelation came to me. I realized something.”

Tsukiyo's crooked back straightened.

“I realized I could fix this world where great detectives don't exist with my own hands.”

“You mean, you could become a great detective yourself?”

Tsukiyo answered with a bold, fearless smile.

“And so, I trained myself to acquire all the skills necessary for the role. Fortunately for me, I turned out to have talent. My skills improved rapidly, and whenever I heard rumors of difficult cases the police couldn't solve, I would solve them myself.”

“The police must have hated you.”

“Of course,” Tsukiyo said cheerfully. “I've been yelled at not to interfere with investigations so many times. I've even come close to being arrested. But I kept investigating, and despite all their interference, I was able to uncover the truth behind the cases. As I continued on that path, the police gradually began to recognize my abilities and informally ask for my cooperation with mysterious cases. As a result, I began receiving constant requests to investigate.”

“And thus was born the great detective Aoi Tsukiyo.”

Tsukiyo nodded, satisfied.

“More than anyone else in this world, I am a woman who has always longed for great detectives. Whether in fiction or reality, I've always admired fantastic, cruel murders and the great detectives who resolve them. That's why...”

Tsukiyo's face contorted in pain.

“I was disappointed when I saw Ms. Tomoe at the crime scene. I was disappointed from the bottom of my heart.”

Tsukiyo's head dropped helplessly as she forced the words from her throat.

Perhaps it was because her ideals were too grand that she couldn't forgive herself for failing to save Madoka as a great detective. Thinking that, Yuma frantically racked his brains.

On his own, there was no way he could find the truth behind the locked room murders that had taken place in the Tower. To find the one who'd killed Oita and Madoka and place the blame for the murder of Kozushima on them, he needed Tsukiyo's help. So what he needed now was for Tsukiyo to regain her confidence and push on to solve the case.

How could he do that? How could he get her to once again confront this difficult case as a great detective? Nervously, Yuma slowly began to speak.

“Is it okay for a great detective to just give up on a case?”

Tsukiyo looked up at him and said “Eh?”

“I understand that your faith in yourself as a great detective wavered after you failed to save Ms. Tomoe. But if you turn your back on a case that's right in front of you, won't that bring you even further from being a great detective?”

Tsukiyo leaned forward, looking like she was intrigued.

“It may be true that great detectives are contradictory beings. They often fail to prevent crimes that take place right in front of them, and sometimes their presence leads to even greater harm. But there is one thing that all great detectives have in common.”

Yuma paused and met eyes with Tsukiyo.

“They never give up.”

Tsukiyo's body began to violently tremble.

“The great detectives I know never give up on their investigations, no matter how difficult things get, pushing on until they corner the culprit and uncover the real truth behind the case.”

Yuma's voice gradually filled with passion as he felt a sense of accomplishment well up within.

“It would have been ideal if we had been able to stop the crime before Ms. Tomoe became a victim. But that crime has already happened. No matter how much you wish, the dead can never be brought back to life. Even though it's painful, what we need to do now is continue the investigation without giving up, reveal what really happened in this Tower, discover the culprit's true identity, and make them pay. As a great detective, that's your duty. If you turn your back on that, you will no longer be a great detective. You'll lose everything you have and everything you've sought.”

Yuma rose from the couch and looked straight into Tsukiyo's eyes.

“So don't look so down. Do what you need to do. Become your true self once again.”

“What I need to do... My true self...”

Tsukiyo's eyes, which had been dark and clouded ever since she'd first seen Madoka's body, suddenly lit up with an indomitable spirit.

“Thank you, Yuma. I was so shocked that I forgot myself. You're right. No matter the situation, all I can do is work to fulfill my role.”

Tsukiyo held out her hand. Yuma took it without hesitation.

“You're the best Watson I could have asked for. Now, let's start over from one. But first, do you mind getting me some coffee? I need caffeine to restart my little grey cells.”

“Yes, madame great detective. Your wish is my command.”

Some coffee was a small price to pay. Besides, Yuma wanted some coffee himself to clear the sleep deprivation induced haze over his heavy head. Yuma crossed the room to the kitchenette, placed a paper filter in the coffee maker, and poured in the complementary coffee grounds.

“Since we want caffeine, I think it would be better to make something on the strong side.”

Yuma poured hot water over the grounds, and a rich aroma filled his nose. At that moment, Tsukiyo suddenly shouted “Who's there!?” Yuma turned around, coffee pot in one hand.

“What's wrong?”

“I heard a sound at the door. Someone's there!”

Tsukiyo quickly ran to the door, unlocked it, threw open the door, and looked both ways.

“I know I heard footsteps.”

“Really!?”

Yuma rushed over and joined Tsukiyo in looking out the door. There was no sign of anyone anywhere he could see.

“I can't hear them now, but I'm sure. Someone was listening at the door, and they ran away when I noticed them.”

“Who was it?”

“I don't know. But it's extremely likely they're connected to the case. Yuma, check upstairs. I'll go down.”

With that, Tsukiyo ran out of the room, descending the spiral stairs two at a time. Her figure soon vanished behind the glass wall.

“Even if you tell me that...”

Unable to keep up with what was happening, Yuma did as he was told and quickly made his way upstairs. Footsteps echoed off the glass. Yuma couldn't tell if they were his, Tsukiyo's, or the person who had been listening through the door.

Had that person even existed? Maybe Tsukiyo had been mistaken. Yuma shook his head to clear the doubt from his mind.

Tsukiyo was a great detective with many skills specialized for criminal investigations. If she insisted there was somebody there, it wasn't likely she'd made a mistake.

In that case, who had eavesdropped on them? His feet slowed.

Everyone in the Tower knew that Tsukiyo was a great detective. There was one person who would have wanted to know more than anyone else how close she was to the truth. Without a doubt, it was...

“The one who killed Mr. Oita and Ms. Tomoe...”

Yuma shouldn't go after them without a clear plan. The person he was facing may have been a killer who had already brutally slain two people. He needed to proceed carefully without letting his guard down.

Yuma took a deep breath and climbed the stairs, body tense.

He couldn't turn back. If he could catch them, he might be able to find out who the culprit was.

He passed the doors engraved “Third”, “Second”, and “First”. He didn't see a single other person. He kept climbing higher and higher, finally reaching the stairwell to the display room. He used the key to the Fourth room to unlock the door and gripped it with sweaty palms. The door opened with a squeal.

Entering the display room, Yuma took a quick look around, wrapping his arms around himself to protect himself from the cold. He couldn't see anyone, but the space that contained the Kozushima Collection had many blind spots. Someone could have been hiding there. Always on guard, Yuma carefully made his way through the display room.

“...There's no one here.”

After spending a few minutes searching the display room, Yuma mumbled to himself. He had performed a thorough search, but he couldn't find anyone. Had Tsukiyo been mistaken, or had the eavesdropper run off downstairs? Either way, the next move was to go back and meet with Tsukiyo.

Yuma returned to the stairwell. He went back downstairs, listening to his footsteps echo off the glass walls, and as he passed the Fourth room, he had a sudden sense of deja vu. A memory flashed through his mind: the first night, when he'd returned to his room after killing Kozushima. He'd had the illusion that someone was following him.

Why was he thinking about that now? The question froze him in his tracks. Yuma's eyes went wide.

He could hear footsteps. Even though he'd stopped, the faint sound still tickled his eardrums. Perhaps Tsukiyo was coming up. Or perhaps...

The moment he tried to turn around, he felt a gentle push on his back. In a horrible slow motion, Yuma felt himself lean forward.

His hand reflexively shot out, but only caught air. His world spun. Then, there was a violent impact on the side of his head. Yuma grit his teeth as a white curtain descended over his consciousness, then curled into a ball, preparing for further blows.

Shoulders, arms, hips, knees, legs, head – Yuma's body tumbled down, hitting a new part every stair, until he finally came to a violent halt when he hit the glass wall.

The pain that ran through his body was so intense he struggled to even breathe. His vision was blurred to the point of incomprehensibility. Did he have a concussion?

Someone had pushed him down the spiral staircase. But who? How?

He was sure he'd confirmed there was no one on the stairs or in the display room.

There is something evil haunting this tower

Yumeyomi's scream echoed in his ears.

Perhaps that sense he'd had on the first night hadn't been an illusion. Perhaps an evil spirit had been wandering the Tower and pushed him from behind.

“...Don't be ridiculous,” a thin voice escaped from his mouth.

He'd heard footsteps. Ghosts didn't have feet. He'd been pushed by a human. An invisible man...

The empty dungeon cell with the open door flashed through his mind. Had someone been locked up in there? And if that person had managed to escape the dungeon without starving, were they still lurking in the Tower?

A dense haze fell over his mind, saturated with questions. His thoughts faded away as his vision darkened. At that moment, he heard footsteps again.

Perhaps the person who'd pushed him had come to finish the job.

He needed to get away. But as though the nerves connecting his brain and body had been severed, he couldn't move a single finger. The footsteps drew closer.

Was this it? Just as despair and resignation filled his heart, a familiar voice rang out.

“Yuma! What happened? Are you okay? Pull yourself together!”

The image of Tsukiyo's face, eyes filled with tears, filled his blurred vision as Yuma's consciousness went black.