The volcano grows quiet. But somewhere nearby, a killer is already waking up…
A group of students—four members of the Kyoto Society of Detective Lovers among them—sets up tents on the slope of the sleeping volcano Yabukiyama. Under the light of the full moon, they sit by the campfire and, for fun, stage a “mystery”: drawing lots to assign the murderer and the victim, and building theories as in a real detective story. It seems that ahead lies friendship for life. But the peaceful night turns into a nightmare…
The volcano suddenly comes to life, and the eruption buries the only road down: there is no way to get out, and no contact with the outside world. And that’s when the game stops being a game—one of them is found murdered. Next to the body lies the letter Y. What is it: a sign left by the criminal or the final clue left by the victim? Under the weight of a sinister secret, their carefree attitude disappears, giving way to suspicion, fear, and a desperate hunt for the truth…
And this murder will not be the last. In the spirit of classic honkaku, the author honestly challenges the reader: you know exactly the same as the person who will solve this deadly mystery—will you be able to unravel it before the finale?