Airi, who married into the Hitomatsu family, began living with her husband and his stepson. While the stepson acted obediently in front of his father, he completely changed around Airi, resenting her attempts to act like a mother figure. One day, while the husband was cleaning, he discovered a video camera. Unaware it was still recording, he accidentally captured footage of Airi. Several days later, when he remembered the tape and watched the contents, he could not hide his shock. The footage revealed Airi being taken by his son—first resisting, then reluctantly accepting, and eventually craving it herself. Gradually, it became clear that his wife was becoming the son's woman, day after day.