Yui started dating Mitsuhiko, whom she met at a part-time job. Mitsuhiko invites her first girlfriend, Yui, to her home to introduce her to her father. Kozo, who has been living without women since her wife passed away with Mitsuhiko, is fascinated by Yui despite his age. One day, Kozo approaches Mitsuhiko by pretending to take advice from Yui, who had quarreled with Mitsuhiko over a trivial matter. Behind the innocent love, Kozo and Yui's unscrupulous physical relationship deepened.
