The Detective Is Already Dead Novel Volume 5 is written by Nigozyu with illustrations by Umibouzu.

Kimihiko Kimizuka has survived the battle with Seed, but not without heavy casualties. Natsunagi is dead, Charlie is in critical condition, and Yui has been taken captive. Kimihiko is lost in despair, but Siesta appears before him to pull him back into action. He can't give up yet. After all, this story needs a happy ending, and what's an assistant without a detective?