Daimon-sensei serves as a teacher at Ousai Academy and the advisor to the Judo Club. He is one of the few regularly appearing teachers and the only male teacher with multiple appearances in the series. His role involves training Judo Club members to a high competitive level, enabling their participation in interhigh competitions soon after the club's founding.

Physically, he is tall and imposing, standing even taller than the notably tall student Takatoshi Tsuda. He maintains a strong physical condition appropriate for instructing martial arts. His appearance features a thick brown beard without a mustache and sideburns connecting to the hair at the back of his head, while the top of his head is bald. This baldness causes him personal concern, leading him to nervously ask his fiancée if his head appears overly shiny.

His personality exhibits a gruff and strict exterior, effectively commanding discipline, such as ensuring Naruko Yokoshima behaves during a school trip. Beneath this, he possesses a gentler side, particularly evident with his fiancée, Michishita-sensei. Their relationship shows mutual affection; for example, during a field trip to Okinawa, he collected star sand for her solely because she mentioned wanting it. He becomes embarrassed if this softer aspect is observed and attempts to conceal it with bluster. He also displays occasional forgetfulness, such as neglecting to warn Mutsumi Mitsuba about an impending interview and photography session for the Judo Club.

Daimon-sensei is associated primarily with Ousai Academy and the Judo Club Room. His background includes being the second male teacher introduced in the series, following a brief appearance by a mathematics teacher in an earlier episode. No significant character development or expanded background beyond these details is depicted across official media.