Susumu, who has left her mother, Reiko, and lives in a share house in Tokyo, is eagerly waiting for next week's "Large Holiday".The reason for this is that he had invited Reiko to her house, aiming for the moment when her roommate vacated her house during the long holidays.On the day of their arrival, Reiko arrives at the share house where Susumu lives.Reiko and Susumu opened her door and silently kissed each other.From that moment to the moment when Reiko returned 24 hours later, the incest of the two began.