Inspector koumei from nagano is a childhood friend and rival of inspector yamato. they attended the same elementary school where they first met. a book titled "komei-kun from second second grade class a!" was based on koumei's exploits in solving cases at an elementary school, while another character in the book was modeled after yamato. the author of the book was also a friend of koumei who passed away. initially, koumei was a high-ranking inspector in nagano until he left his job briefly to search for yamato when he was critically injured during an investigation. after finding the suspect and saving yamato's life, koumei was demoted as an inspector in a local force in nagano. however, it is later revealed that he has effectively returned to the main headquarters.
komei is generally calm and composed, while yamato can be quick-tempered. while investigating, koumei often ignores others and goes out of his jurisdiction to solve cases. he is willing to put himself in danger if necessary. the rivalry between yamato and koumei is mostly friendly, with them competing to see who can solve the case first. yamato has even risked his life to save him once. despite this, yamato has tried to get komei back onto the regular force.