Five years after remarrying, Rin spends her days feeling somewhat unfulfilled. Her stepson, Kakeru, who tends to be a shut-in, creates a constant sense of quiet tension within the home. One day, after accidentally seeing his stepmother's nipples in the bathroom, Kakeru becomes aroused and attacks Rin while she is cleaning. He relentlessly tortures her nipples to confirm her sensitive reactions. Each time he touches her, Rin's body responds, and despite her initial resistance, she begins to feel pleasure. Their relationship continues, with Rin often coupling with her stepson immediately after her husband has left for work. Eventually, she falls so deep that she begins to seek him out herself. A forbidden drama that densely depicts a story of immorality and dependence, starting from the nipples and leading to her downfall.
