It suddenly comes to the ordinary daily life of Satomi Kimura, her mother, and her only son, Shohei. One day, Shohei, who was taking a bath first, suddenly holds Satomi’s crotch and faints in agony when he sees Satomi naked after entering. Satomi is panicked by Shohei’s accident. When Shohei removes his hand from her crotch, there is a fully erected penis. The two are puzzled by the first event in their lives. When I ask Shohei why he got an erection, Shohei replies that she saw Satomi naked. Satomi is skeptical that her mother’s nakedness will make her son erect. After her erection subsides to confirm her authenticity, Satomi shows Shohei her naked sexy pose. Shohei reacts immediately and faints in agony. Satomi is bewildered when he realizes that Shohei’s explanation is because of her own nudity. Satomi guesses that the cause is the taut foreskin of her glans part after thinking that she wants to do something about her fainting even if it can’t be helped. So she decides that Satomi herself will peel her foreskin and she will use a private lotion to proceed smoothly. She finds out she’s getting fed up though, and she reluctantly decides to use her own spit. She wets the tip of the penis with her tongue and occasionally puts it in her mouth. However, Shohei pleads with Satomi to continue her act even after she’s stripped. Satomi continues her act while wondering about it. After a while she finds out that something from Shohei’s penis is ejected into her mouth, and when she spits what she ejects into her hand, she realizes that it is sperm. Shohei, who experienced her first climax and tasted it, then calmly demanded Satomi to fuck her. Satomi continues to answer Shohei’s demands for the sake of her beloved child, but in the end…