The story of two pairs of mothers and sons. Tatsuo Shiiiba, a son who goes to a university in the city and lives alone. For home renovation, his cousin Masaru Saegiki and aunt Saegiki Makiko are staying at his mother Shiiiba Narumi's house—his childhood home. One day, Tatsuo returns home as planned but cannot suppress his sexual arousal towards his mother, leading to multiple instances of intercourse and internal ejaculation after obscene fantasies. Around the same time, Masaru begins to recognize his own mother Saegiki Makiko as a woman and struggles with inner turmoil. He even witnesses the incestuous acts between Narumi and Tatsuo.
