On the day her son's best friend, Koichi, comes to visit, Yukari finds herself alone with him. Koichi suddenly confesses, "I want to know a woman's body." Aroused and overcome with emotion, Yukari makes a bold decision and allows Koichi to give her a blowjob. However, her son walks in and witnesses the act. Shocked yet intensely aroused, the son returns to his room and masturbates while sniffing his mother's panties. Later, when Yukari comes to apologize, her son confesses his true feelings. This moment sparks a new, forbidden relationship between mother and son.