The Detective Is Already Dead Novel Volume 3 is written by Nigozyu with illustrations by Umibouzu.

After being kidnapped, Kimizuka, Natsunagi, Saikawa, and Charlie have learned the truth about Siesta’s death...or have they? A girl who looks just like the deceased detective appears and informs them that the footage they’ve been investigating contains an error. As they hunt for an answer to a mystery that even Siesta couldn’t uncover, the group will learn what it truly means to inherit the legacy of an ace detective. The detective is already dead, and the truth of her death has been already been revealed, but it’s still too early for the epilogue.