Masakazu has lived in a single-parent household since he was a child. This summer, his father, Noboru, remarried with Honoka, a subordinate at his company. As expected of a father and son, the young and beautiful Honoka is exactly what Masakazu likes, and he has lewd fantasies about her every day. One day, Masakazu, Noboru, and Honoka go on a short trip to a local hot spring resort to celebrate their remarriage. However, Noboru is called away from the resort by work and has to leave. And so begins an immoral sexual feast...