Hinako Nakayama, from Kenka Banchou Otome - Girl Beats Boys, has spent her whole life in state-run orphanages, never knowing who her family is. As Hinako prepares to start high school, she is contacted by Hikaru, a kid who claims to be her twin brother. Hikaru and Hinako, according to Hikaru, are the offspring of the powerful Onigashima yakuza family's boss, and Hikaru wants Hinako to swap places with him at Shishiku Academy, an all-boys school overrun with the nation's worst delinquents. Can Hinako save her brother, find love, and become the school's next principal?