Reiko Kitagawa is invited by her husband Takaki on a hot spring trip. Upon arriving at the inn, Reiko heads straight to the bathhouse, where the head attendant suddenly appears, approaches from behind, and starts stimulating her anus while groping her buttocks. Fleeing back to her room in panic, she finds another attendant lying in wait, who proceeds to penetrate and defile Reiko's anus—a place her husband had never touched. Unaware that her husband had secretly drilled a hole in the sliding door to voyeuristically pleasure himself while watching, Reiko remains ignorant of the trip's true purpose: having her anus taken by other men.