妊娠中の妻と妻の実家へ帰省した僕。ある日、畳の部屋から卑猥な吐息が聞こえてきた。こっそり襖を覗くと義母・まりこさんが自慰に耽っていた。激しく興奮した僕も隠れて相互オナニーをしてしまう。するとまりこさんはそんな僕に気付いて「娘には内緒だよ？」と言いその日の夜、川の字で寝ている僕を襲ってきて…。
My pregnant wife and I went to her parents' house for a visit. One day, I heard lewd sighs coming from the tatami room. I secretly peeked through the sliding door and saw my mother-in-law, Mariko, masturbating. I became intensely aroused and secretly joined in, masturbating together. Mariko noticed what we were doing and said, "Don't tell my daughter, okay?" That night, as we were sleeping side-by-side, she attacked me…

– JavGG.net