Ryuukouji Kai

The daughter and the only successor of Ryuukouchi Zaibatsu, Kai is brought up like a boy and has a lot of masculine characteristics. She is very good at fighting and does not hesitate to beat up anyone who annoys her. This makes her a frightening figure among the local thugs. Her closest friend is Yu Satsuki.

At school, Kai is a delinquent, hardly going to class or participating in any activities. During school, she spends most of her time taking a nap on the rooftop, chilling out at Kirameki riverside park, or going to game arcade. Despite her delinquency, Kai does surprisingly well in exams and often stays among the top of the class.