Susumu, who left his mother Reiko and is living in a share house in Tokyo, is eagerly awaiting next week's "long holiday." The reason is that he has invited Reiko to his house, aiming for the moment when his roommate will be away from home during the long holiday... And on the day of the holiday, Reiko comes to the share house where Susumu lives. Reiko and Susumu open the front door and kiss without a word. From that moment until the moment Reiko returns home 24 hours later, the two begin their incestuous relationship.