Kappei, a tall Misaki High School student with black hair and brown eyes, dresses in his school uniform or casual outfits like a black t-shirt layered under a vibrant blue and yellow coat, often sporting a blue hat. His friendly yet occasionally awkward demeanor shines in his persistent but unsuccessful attempts to invite classmate Ayane Mitsui to kickboxing events, despite her repeated rejections. Alongside Kayoko Nakajima, he forms a trio marked by easy camaraderie, united in their enthusiastic support for Ayane’s kickboxing pursuits.

Kappei’s loyalty surfaces during Ayane’s matches, where he cheers loudly, critiques her techniques, and celebrates her wins, often snacking on popcorn while immersed in the action. His accidental drop of a kickboxing ticket—later discovered by the principal—hints at his dedication to sharing his passion. When Ayane faces an unexpected challenge from rival fighter Sakurako Miyagawa, Kappei’s shock underscores his initial unawareness of her newfound commitment to the sport, contrasting her past indifference.

As an active member of the kickboxing fan community, he frequently brings magazines featuring Ayane to school, blending his fandom with daily life. His bond with Kayoko thrives on mutual encouragement, their dynamic rooted in spirited advocacy for Ayane’s ambitions, reflecting a friendship built on shared enthusiasm and unwavering support.