A package arrived at the home of Eri, her mother-in-law, who was frustrated due to lack of sexual activity. Hesitantly, she opened it to find erotic lingerie and a vibrator inside. Without a second thought, she used them, believing the letter that said they were for free monitoring. However, it was actually a trap set by Hideki, her son-in-law, who wanted to possess Eri's large breasts. Hideki, who had been filming the scene, now approaches Eri's body!