A beautiful mother, Aoi, lives with her son. Although they live happily every day, she feels lonely as she has not been able to see her husband, who is away on an overseas assignment for long periods of time. One day, her son's best friend, Yuu, comes to stay for a club activity. Yuu has had feelings for Aoi since childhood, and suddenly he kisses her. Aoi feels an uncontrollable pounding in her heart, despite her own will. After that, Yuu comes on to her, and Aoi has his lips stolen once again, and the unfaithful desires that she has been suppressing are ignited...