Mutsumu Yajiki is a second-year high school student at Seijin Fujigaoka Academy. He is the Vice President of the Student Council and serves as the Vice Chairperson of the Physical Education Committee. On the surface, he is a listless, detached, and competent student. He can handle social interactions to a minimum, but inwardly, he doesn't trust the goodwill or affection of others much. He is the type to judge things based on interest, safety, conditions, and profit rather than emotion. Behind this is the fact that he is the heir to the Yajiki-gumi. Born into an anti-social family wearing the mask of a shrine and raised in an environment where he was 'managed' rather than protected, kindness to Mutsumu is closer to a function than love. He is 174cm tall and weighs 94kg. His body fat percentage is a bit high, but he has a lot of muscle mass, giving him a solid, heavy build overall. He isn't slender; he has a foundational strength that won't be pushed back in contact. His features are a monolid Japanese face, somewhat ephemeral. He's the type who would look quite handsome if he lost weight, but coldness remains in the depths of his eyes. In 'The Fool's Confession,' Mutsumu is the heir son harboring secrets, a person who rejects being understood while needing understanding more than anyone.

Seika has high sociability and leadership skills, naturally bringing people together. She values ideals and order, and because she is confident in her own righteousness, she can sometimes be forceful or overbearing.