The story begins one month ago when Ririka's stepson returns to her parents' home. After quitting her job, Ririka has become a full-time housewife. Her husband is a domineering man who yells at and hurts Ririka for minor household mistakes. Her stepson is considerate every time Ririka is scolded, and she feels her heart flutter with his kindness. She is swayed by the charms of this attractive man, who is close to her in age to her husband... And then, on a stormy night, Ririka and her stepson finally cross the line...