Yumi works hard at her ramen shop while taking care of her son, always maintaining a cheerful smile. However, her son Kazuo harbors an abnormal affection for her, creating a tense and complicated family atmosphere. One day, a new male employee is hired at the ramen shop. One night, the man is drawn to Yumi's beauty and the two begin a physical relationship. By chance, Kazuo witnesses the pair indulging in BDSM play. Torn between his forbidden feelings and reality, he begins to cross the line.