Fumiko is on a trip to a hot spring with her husband and son. Her husband had been so focused on his work that he hadn't had time to spend with his family, but after he was injured, he realized how important family is and decided to take this trip. Her son had been skipping school, but through spending time with his family he gradually started going to school. Meanwhile, the one thing that bothers Fumiko is that her son is secretly masturbating with his mother's underwear. Fumiko has noticed this and pretended to be calm, but on this trip her son finally takes action...