Aoi, the mother-in-law, visited her daughter's family after a long time. With her calm and kind personality, she was warmly welcomed by her daughter Chiaki and her husband Tatsuya. However, during their casual conversation, she found out about the 'nighttime issue' between them. One night, Tatsuya was strongly drawn to a glimpse of his stepmother's figure he happened to see and began to harbor an uncontrollable desire. Later, unexpectedly, the distance between Aoi and Tatsuya rapidly closed, and they found themselves advancing into a relationship they should not have entered. Initially confused, Aoi begins to feel her emotions as a woman stirred. Meanwhile, Tatsuya is increasingly drawn to his mother-in-law amidst an unsatisfying marital relationship. The two struggle with their familial roles and sense of taboo but deepen their secret relationship. Eventually, the pent-up feelings cross a decisive line, and the relationship escalates further. Amidst this, an event that shakes everything occurs: daughter Chiaki witnesses the relationship. Three people sway between family bonds and desire. As their emotions clash, the story heads towards a tense conclusion.
