Yui becomes romantically involved with Mitsuhiko, a coworker from her part-time job. Wanting to introduce his first girlfriend to his father, Mitsuhiko invites Yui to their home. Widower Takazou, still grieving his late wife, finds himself increasingly attracted to Yui despite the age difference. One day, pretending to comfort Yui after her argument with Mitsuhiko, Takazou takes the opportunity to get closer to her. Behind their pure-seeming romance, an illicit affair quietly develops between Yui and Takazou, gradually deepening over time.