Yui begins dating Mitsuhiko, whom she met at a part-time job. Mitsuhiko invites Yui to her home to introduce her, her first girlfriend, to her father. After losing his wife before Takazo had lived a womanless life with Mitsuhiko, but despite his age, he was fascinated by Yui. One day, Takazo pretends to take advice from Yui who has a fight with Mitsuhiko over a trivial matter, and approaches Yui. Behind the scenes of her innocent love, the indecent physical relationship between Takazo and Yui deepens.