After her husband's death and the completion of his third-year memorial service, Mayuko decided to live with her son and his wife. Although they were initially tense with each other, it seemed they had built a good relationship and were living harmoniously. However, Mayuko felt lonely without her husband and found herself turning to self-pleasure as a daily routine to distract from the ache in her body. One late night, while she was soothing her aching body, her son caught her in the act. Just as she reached climax through self-pleasure, her son appeared and forcibly inserted his erect penis into her body. Despite being coerced, Mayuko found herself complying with the act. Over time, Mayuko began to initiate encounters with her son. It was then that Mayuko noticed something unusual about her body: her period had stopped. Feeling that she was no longer a woman in every sense, she told her son and tried to end their relationship...
