Kaoru lives with her daughter and son-in-law, and one day accidentally discovers that the couple is suffering from a sexless marriage. Seeing them silently longing for each other, she begins to reflect on her own loneliness. Unbeknownst to her, the son-in-law has become intensely aroused after catching sight of Kaoru's obscenely large breasts. Unable to resist his passionate advances, Kaoru's heart and body gradually give in, and the two begin a forbidden affair under the same roof. The man who was once merely a family member living with her has now become someone who tightly binds her. A story unfolds where sorrow and temptation intertwine, revealing how this illicit, taboo relationship continues to evolve.