After realizing her son Haruo is still a virgin, mother Ayako finds herself overwhelmed by daily stress and pent-up desire, driven by an uncontrollable urge to take his body. Skillfully executing her plan, she successfully deflowers Haruo—but the outcome exceeds all expectations. Rather than losing his erection, Haruo's penis grows even more excited, immediately ready to thrust into her again. Initially attributing it to youthful vigor, Ayako grows increasingly shocked and flustered by Haruo's relentless stamina, unable to hide her bewilderment as he instantly re-erects no matter how much she stimulates him. Attempting to escape by slipping away into the bath, she's caught off guard when Haruo suddenly barges in, driving the story into even deeper territory.