Four coworkers—Hanami and her husband Gorō, along with Yanagida and his wife—are enjoying a hot spring trip together. Gorō has joined this journey with a specific goal in mind. Excited and aroused, Hanami becomes increasingly lustful, openly craving her husband's cock. Her moans carry into the next room, where the Yanagida couple overhears them, sparking their own desire and prompting them to demand sex. Gorō attends to Hanami, fulfilling her needs—but this encounter is actually a crucial part of his carefully laid plan.