Although she is on good terms with her husband, Umi spends her depressing days without being blessed with children. One day, her brother-in-law, Kyoichi, visits her house for a memorial service. Kyoichi, who has a strong sexual desire and loves women, relentlessly pokes at her lust hidden deep inside. "I was just swept away..." Umi tells herself, and she has a one-time relationship. However, the relentless caress that is different from her husband's, the stimulation of her cock that penetrates her brain, she is immediately overwritten by her pleasure. And Umi suddenly fell into a secret affair with her brother-in-law...