The Detective Is Already Dead Novel Volume 6 is written by Nigozyu with illustrations by Umibouzu.

Siesta and Kimihiko’s first meeting did not take place during that fateful plane jacking, but rather four years earlier. During that time, the federal government tasked Siesta with locating a spy in Japan, where she happened upon her future assistant. The secret of why the great detective took Kimihiko under her wing is finally revealed in this prequel!