The celebration of the wedding of Ikuyo, the younger sister of the prestigious Kameto family, and Sashiko continues late into the night. Since the death of their grandmother, Tatsuyo, a rumor has been circulating in the Kameto family that a "succubus has returned." While Ikuyo waits in the bedroom for Sashiko to go to the bath, she is immersed in pleasure and masturbates, when suddenly she is attacked by a demon...