Ryo lives with her husband and son. As her son began working and she found herself alone more often, she started masturbating to cope with the loneliness. One day, her son came home drunk, upset after being yelled at by a senior at work, and began venting his frustrations. Ryo gently hugged and comforted him, but in that moment, her son said, "I want your breasts," exposed her chest, and started sucking her nipples. Overwhelmed by the sensation, she lost all will to resist and ended up accepting his cock. From that day on, she was drawn into a continuing relationship with her increasingly affection-seeking son. The story depicts the gradual shift in family dynamics, as forbidden emotions between mother and son deepen.