Unsatisfied with her sex life with her husband, Tsuyako Yamamoto is targeted by her stepson Yoshio, who gradually trains her to become his sex slave. Initially resisting and filled with shame, she inwardly denies her desires, yet her loneliness causes her body to increasingly submit to the boys' lust. Each time Yoshio's friends visit the house, Tsuyako begins offering her body to them, eventually craving their cock on her own. Her body is repeatedly taken by the men, transforming her into someone who willingly surrenders herself completely.