The story of two pairs of mothers and sons. Tatsuo Kazuki, a son who lives alone while attending university in the Tokyo metropolitan area. For home renovations, his cousin Masaru Hoshi and aunt Sayano Hoshi are staying at his mother Sakura Kazuki's house, which is also Tatsuo's childhood home. One day, Tatsuo returned home as planned but couldn't suppress his sexual arousal towards his mother, leading to multiple acts of intercourse and internal ejaculation after obscene fantasies. Around the same time, Masaru was building a forbidden master-servant relationship with his own mother Sayano. Then, they both witness the mother-son incest in the Kazuki household.
