Out of the thousand girls attending Hachimitsu Academy, five best friends—Kiyoshi Fujino, Takehito "Gakuto" Morokuzu, Shingo Wakamoto, Jouji "Joe" Nezu, and Reiji "Andre" Andou—are the only boys in the school. Kiyoshi meets Chiyo Kurihara, an avid sumo fan and becomes the first of the five to have talked to a girl; they decide to go to a sumo tournament. Later, Kiyoshi's friends formulate a plan to record video of the girls' baths. When Kiyoshi drops his phone inside the bathroom, he sneaks in to retrieve it. Chiyo discovers him, but mistakes him for her friend Mayumi. However, the Underground Student Council (USC) catches Kiyoshi's friends, and ultimately Kiyoshi is also caught by their President, Mari Kurihara. As punishment, the five are sentenced to one month in the school's prison, where Kiyoshi becomes awestruck at the guys' masochistic outlooks after the constant abuse by the Vice-President Meiko Shiraki. Shortly after, Meiko enlists the help of Hana Midorikawa, the USC's Secretary, to oversee the boys. After Kiyoshi tends to a baby crow, he meets Chiyo and promises he will meet her at the sumo match. As Hana attempts to urinate beneath him however, a crow knocks him off the tree branch and he witnesses Hana urinating, much to her embarrassment.