High schooler Kyosuke Shikijo stands out as the most skilled participant in his school’s martial arts club. Following in the footsteps of his late father, who was a detective, Kyosuke possesses a strong sense of justice. However, he harbors a unique secret: he enjoys wearing women’s underwear, which allows him to transform into his alter ego, “Hentai Kamen.” This peculiar habit is rooted in his family background, with his father being a masochist and his mother a sadist. One day, Kyosuke accidentally acquires the underwear of a fellow student, Aiko Himeno. With her underwear, he gains a variety of unconventional abilities and sets out to protect Aiko from a corrupt and vile teacher.