Mirei is captain of the swimming club. She is very beautiful and an expert swimmer. Kurumi is a member of the swimming club as well. But she is very poor at swimming. When she is about to quit the club, Yuya, vice captain of the swimming club, offers her to teach swimming after school. She accepts it and they practice hard at night every day. One night, he suddenly gets sexually aroused and rapes Kurumi... But he is not satisfied yet... "I'll rape Mirei as well..."