* Based on the manga by Oogure Ito. The first-years Nagi Souichirou and Bob Makihara entered Tendou High School with the intent of taking it over — only for Souichirou to get soundly defeated by Natsume Maya, the sexy captain of the Jyukenbo martial arts club, who can change her body at will to that of her child-self. Souichirou is further humiliated in his complete loss against Maya's subordinate, Takayanagi Masataka. Things get more complicated as Maya's little sister, Aya, asks the girl-shy Souichirou to marry her, and tells him to promise never to lose another fight... A day or so after their violent debut at Tendou High School, which turns out to be a martial arts centred institution, the Enforcers, the school discipline team, moves in to punish the upstart freshmen. It does not take long before Souichirou and Bob realize their weakness in comparison to Maya, Masataka, and the Enforcers, and join the Jyukenbo with the promise of becoming stronger than any of the current members, within three months. Aya, in conflict with the Enforcers, whose president is Masataka's older brother, welcomes them in hopes of Souichiro finally realizing her goal...