Yusuke is an ordinary high school student except that he mistakenly entered a boy's high school. There is no sweet love romance at school.... His one and only hope is... to work at a seaside restaurant during summer holiday and meet girls in swimsuit there. But on the first day of summer holiday, he is hit by a bicycle and twists his ankle.... Yusuke has two sisters and they take good care of him. He needs to stay at home but his parents leave him and go traveling... and he starts to live with sisters for a while....