Mai Nanase is Yukihiro's younger sister. She is a naive high school student who one day overhears her brother's friend, Sota Nishino, saying "Your sister is cute." They then start a relation... Read allMai Nanase is Yukihiro's younger sister. She is a naive high school student who one day overhears her brother's friend, Sota Nishino, saying "Your sister is cute." They then start a relationship, however, Sota's cousin, Ituski Kaga, also falls in love with Mai.Mai Nanase is Yukihiro's younger sister. She is a naive high school student who one day overhears her brother's friend, Sota Nishino, saying "Your sister is cute." They then start a relationship, however, Sota's cousin, Ituski Kaga, also falls in love with Mai.