Hiroshi visits his girlfriend's home and finds himself instantly drawn to her mother, whom he calls Mama. That night, graciously allowed to stay over, he takes a bath and has his groin washed by the stepmother's own hands—sending waves of tingling excitement through his body. Later, as drowsiness overtakes him late at night, he leaves his room and catches sight of the sleeping woman's soft, inviting figure in her bedroom. Overcome by uncontrollable desire, the young man reaches out toward the slumbering stepmother...!