This is a fleeting yet obscene sexual experience that happened 20 years ago... When his mother was hospitalized, Seiichi was sent to live with his mother's cousin Kana. He was Kokoro about the idea of ​​living with his beautiful cousin, but what awaited him was a scene that was too stimulating for his childish Kokoro. Kana masturbating in the middle of the night, and secretly satisfying her son's sexual needs... Seiichi, who was of marriageable age, could no longer suppress his urges and desired Kana's body. Kana, who was sexually frustrated, gradually gave in, and the two developed a forbidden relationship...