Hachimitsu Academy was an all-girls high school until the new school year, as the management board has decided to enroll boys into their system. Now Kiyoshi Fujino and his four friends—Takehito "Gakuto" Morokuzu, Shingo Wakamoto, Jouji "Joe" Nezu, and Reiji "Andre" Andou—are the only male students among 1,000 girls. Adding to their shock, the savage laws still remain effective, and punishment for even the most minor infractions is a stay in the school's prison. A string of perverted incidents lead the five boys to be "convicted" and "arrested", now they must struggle to escape from the prison.