In the year 203X, a security robot goes on a rampage in Shibuya. Nakamura Nao, a police detective, commissions detective Akechi Kogorou to solve the case, but Akechi, along with Inoue Ryou, is already heading toward the robot's manufacturer.

Kobayashi somehow feels that maybe he can die if he stays with Hanasaki, so he joins the Boy Detectives' Club. His first mission is to help find a jobless young man who's gone missing.