"Heya, Kou-chin. You should totally, like, tutor me!" It was the Saturday right after exams. Summer vacation was right around the corner. Muroto Kouta, who was living on his own due to complications with his family, encountered his gyaru classmate, [...]

美少女でおしとやかな妹がなんと切れ痔に！誰にも相談できず打ち明けてきた妹に、兄はさっそく座薬を買ってきたのだが……妹の親友も巻き込んで、事態は更にエスカレートしていくのだった。