Chiaki lives with her stepdaughter and her husband in an apartment. Her husband is indifferent and always frustrated. One night, her stepdaughter, who is interested in her stepmother Chiaki's bewitching body, sees her masturbating and asks her to perform fellatio on him. The next day, her stepdaughter has sex with him, and her stepmother is awakened to womanhood. From then on, she enjoys having thick sex with her stepdaughter and stepson.