Aoi, a mother-in-law, visits her daughter and son-in-law's home for the first time in a while. Gentle and kind, she is warmly welcomed by her daughter, Chiaki, and her husband, Tatsuya. However, through casual conversation, she discovers that the couple has "nighttime problems."
One night, Tatsuya is strongly attracted to a glimpse of his mother-in-law and develops an uncontrollable desire for her. Soon after, in an unexpected way, the distance between Aoi and Tatsuya rapidly closes, and they enter a relationship they should never have crossed.
Initially confused, Aoi's feminine emotions are gradually stimulated. Meanwhile, Tatsuya, unsatisfied in his marriage, finds himself deeply drawn to his mother-in-law. Despite the conflict between their family roles and the sense of immorality, the two deepen their secret relationship.
Eventually, their uncontrollable feelings cross a definitive line, and the relationship escalates further. In the midst of this, a world-shaking event occurs: the daughter, Chiaki, witnesses their affair.
Three people torn between family bonds and desire. As their emotions intertwine, the story heads toward a tense conclusion.
