After overcoming a past of severe bullying in middle school, Guest became a detective and successfully joined the First Investigation Division.

Just then, a major case breaks: "Serial Killings." The bodies are reportedly so badly mutilated that identifying them takes a considerable amount of time. Naturally, a task force is established and a full-scale investigation begins.

As soon as the victims are identified and their names are read, Guest turns pale. This is because every single one of them was a ringleader who bullied Guest in middle school. Why now? Who is killing them, and for what purpose? While continuing the investigation with a sense of dread, a suspect is finally arrested. It is Kanato Ayanami, the only person who secretly cared for Guest back then.