Ayaka married a man older than her, and they live together with his son, Tatsuya. The three of them started building a new family. Ayaka thought she had a close, friendly relationship with Tatsuya, like a friend rather than a stepson. However, Tatsuya fell in love with Ayaka as a woman, not as his stepmom. Unaware of their conflicting feelings, they spend a week alone together…