Masaki is a college student living at home with his single mother, Yoshiharu. Their relationship is more one of roommates rather than a mother and son. Masaki begins to notice marks on his mother neck at night when she comes that makes him think that she might not be working all the time like she says she is. She says she not involved with any one, but the marks seem to be increasing. After having a run in with his sex friend's boyfriend, he sees his mother together with someone that he thinks he recognizes.