Akiko (Yukari) lives with her common-law husband Shozo and their son Kenji. Akiko wants to get married soon, but Shozo refuses to become a father, and Kenji doesn't approve of Shozo doing whatever he wants with his mother, so their relationship is strained. One day, while washing her son's back in the bath to cheer him up, Akiko makes a mistake out of caring too much about him. It was only supposed to be a one-time thing, but the presence of a father who is not related by blood deepens the relationship between mother and son even more...
