The story takes place at a certain middle school where several murder cases take place. Kobayashi, a boy who goes to this school, meets genius detective Akechi, who comes to the school to investigate. Kobayashi takes an interest in Akechi and, in spite of his friend Hashiba's worries, he volunteers to be Akechi's assistant. -- Originally named "乱歩奇譚: Game of Laplace"