At the request of a son who has fallen for his stepmother—his father's new wife—Takagi Takeshi devises a plan to fulfill his desire for consanguineous incest. Takagi, playing the role of a company president harmed by the son's misconduct, manipulates the stepmother into submitting her body. One year after marrying the father, she secretly surrenders herself to the son, pretending reluctance while moaning uncontrollably. Under relentless foreplay, she climaxes while apologizing, accepts his erect penis, and melts with pleasure. Once her vision is obscured, the son—disguised as a friend—joins in, escalating into a threesome. As she is penetrated by the son's cock, she performs a blowjob on the other man, taking the second penis deep into her mouth.