Oira Sukeban follows Banji, the sole male student at an all‑girls school, who must keep his gender hidden to avoid being expelled. Banji’s parents insist he attend a prestigious school, but their finances can only cover a girls’ academy, not a co‑educational one. As a result, Banji is forced to learn how to wear a bra and apply makeup while juggling his studies in math and science. The pressure turns his daily life into a living nightmare: he ranks low in the social hierarchy, must conceal his masculinity from a beautiful classmate who has captured his affection, and constantly evades the cruel female bullies who threaten to expose his secret.