Yura married a man with a child and soon found herself getting along well with her husband, but still struggling to build a relationship with her stepson, Tomoya. One day, Tomoya, who harbors intense sexual desires, asks Yura to help him masturbate. Overcome with joy at being called "Mom" for the first time, Yura agrees to assist her stepson's release. However, one ejaculation isn't enough to satisfy Tomoya, and he continues approaching her whenever he gets the chance. Initially unable to refuse, Yura reluctantly complies—but before long, she begins actively seeking opportunities to help him herself.