“Proof of non-resolution of a locked room is equivalent to proof of absence from the scene of a crime.”
“Therefore, as long as the crime scene remains behind a locked door, the defendant must be declared innocent.”
—Excerpt from the judgment of Tokyo District Court Judge Chiyori Kurokawa
If a locked room murder were to be committed in Japan, would the culprit be found not guilty? I once had that discussion with a friend of mine. Of course, at the time I'd thought we were just making idle talk... The answer was obvious. Why would the culprit have been declared not guilty just because the crime was committed in a locked room? From a perspective of pure common sense, it makes no sense. If it's obvious who the culprit is, they should be found guilty, regardless of whether or not the crime scene was a locked room.
But my friend replied “I think they would be found not guilty.” Stroking her long black hair, she'd said “Isn't it obvious?”
“If a criminal had a perfect alibi, they would be found not guilty, wouldn't they? Because it would be impossible for them to have committed the crime. Doesn't the same thing apply to a locked room? From the perspective of 'making the crime impossible', there's no difference between a locked room and an alibi. Why is an alibi an acceptable defense, but not a locked room? It isn't logical at all.”
I was completely won over to her way of thought all at once. That's a lie, obviously. What she was saying was pure sophistry, and there was no way to prove whether her argument had any truth at all. After all, in the entire history of this country, there had yet to be a single locked room murder.
So when the day came, my values were shattered. Japan's first locked room murder took place in a mansion in Tokyo, and the judge in that trial handed down the following verdict:
“Proof of non-resolution of a locked room is equivalent to proof of absence from the scene of a crime.” In other words, if the scene is a perfect locked room, it's the same as the culprit having a perfect alibi. And that becoming legal precedent meant that from that day on, in any locked room murder in the entire country, the culprit would be found not guilty unless the locked room at the scene was solved.
In a way, at that moment, the judiciary acknowledged the value of a locked room.
Immediately, the number of locked room murders in this country increased dramatically. How much of an increase? Enough to make a third of all murders committed in Japan since into locked room murders.
It was the dawn of a new era that could be called the Golden Age of Locked Rooms, and a dazzling golden light spread the annihilating flames of locked rooms across Japan.
For example... There's a remote village in Tokyo Prefecture called “Yatsuwako Village”.
That village would become the site of what came to be called the “Yatsuwako Village Octuple Locked Room Murder Case”, which broke the record for most consecutive locked room murders in Japan. But back then, I still had no idea how that mystery would end.