Ibuki and Shima go undercover as convenience store clerks to prevent a robbery. However, their plan hits a snag when more than one store is targeted.

Having overheard someone call Shima a partner killer, Ibuki begins to probe into Shima’s past in a bid to uncover the secret he’s hiding from him.

After investigating a body believed to be related to an unsolved serial murder case, Ibuki discovers that his mentor arrested the victim years prior.