Aoi, a woman who has been married to her husband for three years. Far from the initial kindness, I feel lonely in the face of my husband's attitude. When I went to buy dinner during a difficult time, I accidentally ran into my classmate Hosoda from my university days. Aoi discovered that Hosoda worked at a swimming class and was invited for a visit, and decided to join a swimming class. Later, every time I attended the swimming class, Aoi began to be drawn to Hosoda's kindness, who encouraged her worries about her husband. And on the day her dissatisfaction with her husband erupted, Aoi crossed the line with Hosoda...