Ai is 35 years old and feels sorry for her widowed stepfather, who seems lonely since her mother-in-law passed away. When he begins expressing physical desire for her, she is momentarily confused but decides to accept it as an act of filial devotion. Gradually, her feelings begin to shift, and her relationship with her stepfather deepens. Amidst a tender yet bittersweet daily life, Ai confronts her own emotions.