The story of two pairs of mothers and sons. Tatsuo Kamijima, a son who lives alone while attending a university in the Tokyo metropolitan area, has his cousin Masaru Yokoyama and aunt Sayoko Yokoyama staying at his mother Miduko Kamijima's house for home renovation purposes. In other words, they are living as dependents in Tatsuo's childhood home. One day, Tatsuo returns home as planned but cannot contain his sexual arousal towards his mother, leading to multiple instances of intercourse and internal ejaculation after lewd fantasies. Meanwhile, Masaru forces his own mother Sayoko Yokoyama to wear lewd clothing every day. He also witnesses the incestuous acts between the Kamijima mother and son.
