Takuto was repeatedly rejected by his wife due to his oversized cock, so he routinely resorted to masturbating with porn and using his stepmother Mary as his fantasy. However, Mary, dissatisfied with her own sex life, grew increasingly intrigued by Takuto's massive cock and began repeatedly giving him ejaculation services, justifying it as "filling in for your daughter." Before long, Takuto found himself unable to feel satisfied without his stepmother's body. Their wild, uninhibited affair became routine, gradually taking full control over his mind and body.