Kenmochi's supervisor is an extremely intelligent and elite-level police detective, known as Superintendent Akechi. He first appeared in "Death TV" where he was portrayed as arrogant and snobbish, becoming a rival to Kindaichi in solving crimes. Despite his initial demeanor, Akechi secretly assisted Kindaichi in solving the case and getting out of trouble. Their relationship is abrasive at best but they have an unspoken mutual respect for each other's abilities. Akechi often compares Japanese crimes to those he experienced in Los Angeles. He is fluent in English and French. In "The Magical Express," it was revealed that he had met Reiko Chikamiya before her death, which helped Kindaichi solve the case. In "Murder at Hells School," Akechi disguised himself as a math teacher and claimed to have been a teacher in a famous prep school for three years. His name may be a reference to Kogoro Akechi, a classic Japanese detective created by Edogawa Rampo.