The story of two sets of mothers and sons. Tatsuo Okamura, a son who goes to a university in the Tokyo metropolitan area and lives alone. For home renovation purposes, his cousin Masaru Shimura and aunt Tomomi Shimura are staying at his mother Yukihi Okamura's house—essentially, Tatsuo's childhood home. One day, Tatsuo returns home as planned but cannot suppress his sexual excitement towards his mother, leading to multiple instances of intercourse and ejaculation inside her. Around the same time, Masaru forces his own mother Tomomi Shimura to wear lewd clothing. He also witnesses the incestuous acts between Yukihi and Tatsuo.
