The plot of Prison School takes place in the Hachimitsu Girls' High School, which is reputed to be one of the strictest and most prestigious in Tokyo. The director of said institute decides to change the reigime of the school by also admitting male students. Kiyoshi Fujino is one of these new students, and to his surprise he discovers that he and his four friends-Takehito Morokozu, Shingo Wakamoto, Jouji Nezu, and Reiji Andou-are the only male students among 1,000 females, and whose coexistence with them is even more difficult due to the draconian laws and regulations governing the school, which were established by the so-called Underground Student Council, and punishes even the most minor infractions with a stay in a kind of prison that the school owns.
