Aoi, a woman has been married to her husband for three years. Far from her initial kindness, she felt alone with her husband's attitude. When she goes shopping for dinner with her worries, she runs into Hosoda, her classmate when she was a student. There, she learns that Hosoda is working in a swimming class, and Aoi is invited to visit her and decides to go to her swimming class. After that, every time she went to swimming class, Aoi began to be attracted by Hosoda's kindness, which encouraged her husband's worries. And on the day her dissatisfaction with her husband exploded, Aoi crossed the line with Hosoda.
