Kiyoshi Shusse is a member of the eccentric Kimengumi. His family operates a bathhouse where he lives, and he required three attempts to pass his high school entrance exam.

He bears the nickname "Mukiba no Kiyoshi," meaning "Exposed Teeth Kiyoshi," for the distinctive, perpetually drawn toothy smile on his face. Within his friend group, he stands as the most intelligent and rational member, often acting as the strategist for their plans, though this is only relative to his peers. He is also a notorious lecher, frequently caught peering into the women's side of the family bathhouse. His room is adorned with posters of half-naked women. Despite this obsessive interest aligning with tropes like "Lovable Sex Maniac," his attempts at seduction rarely succeed and are sometimes characterized as pure-hearted beneath the surface.

His closest friend in the Kimengumi is Jin Daima. He has a younger sister, Kiyoi Shusse, for whom he serves as a "Cool Big Bro," though this sometimes shifts to a "Disappointing Older Sibling" when her classmates mock his well-known perverted antics. In addition to the "Perpetual Smiler" trope embodied by his fixed grin, he, like all Kimengumi members, possesses "Reality Warper" abilities, manipulating cartoon physics for comedic effect.