Misshitsu Ougon Jidai no Satsujin

In the winter of three years ago, the first locked room mu*der in Japanese history was committed.

All of the evidence pointed to the defendant. It was certain they were guilty. And yet, they were found innocent and released. Why? Because the crime scene was a perfect locked room no one from the police or the prosecutor’s office could solve.

“Since the room was locked, it was impossible for the defendant to have committed the mu*der. It’s no different than if they had a perfect alibi.” That was the argument of the defense, and that was the argument the judge sided with.

The ruling sent a ripple throughout Japanese society. No matter how suspicious you were or how much evidence you left behind, as long as you managed to create a locked room that no one could solve, you were immune from prosecution. With the common anti-mystery fiction talking point “there’s no reason anyone would ever actually commit a locked room mu*der” completely overturned, the rate of locked room mu*ders in Japan skyrocketed.

When the police proved unable to deal with the surge of locked room crime, the Ministry of Justice published an official categorization of all known locked room tricks as an investigative aid. When that proved insufficient, Division Zero of the Tokyo Metropolitan Police Department, a police division dedicated solely to solving locked rooms, was created. When that still proved insufficient, locked room detectives, private investigators specializing in locked rooms, were officially licensed by the state and authorized to participate in police investigations. Calling a locked room appraiser, someone specializing in searching buildings for secret passages, is now a common first step in criminal investigations.

On the other side of the spectrum, locked room agents, assassins and crime planners specializing in locked room mu*ders, have become some of the most notorious criminals in Japanese history, and even a cult worshiping the scenes of locked rooms as a way to purify the souls of the deceased has made rapid inroads into Japan.

The protagonist, Kasumi Kuzushiro, is an introverted, somewhat cynical high school student who loves mysteries. Kasumi often finds himself dragged along on bizarre journeys by his flighty childhood friend, Yozuki Asahina. Due to their staggeringly bad luck, these trips often leave them in the wrong place at the wrong time to be caught up in locked room mysteries. Fortunately, another of Kasumi’s childhood friends, Shitsuri Mitsumura, is the greatest locked room expert in the world, and can always discover the truth.

Hm? How did a high school girl become the greatest locked room expert in the world?

It’s simple.

She’s…

Volume 1 was the grand prize winner of the 2022 This Mystery Is Amazing! awards.