His aunt takes him into a mixed-gender hot spring, where the sight of naked women gives him an obvious erection. The more he tries to make it go away, the harder he gets. Noticing his panic, his aunt discreetly reaches down and gives him a handjob, believing that one ejaculation will spare him further embarrassment. Partway through, however, she becomes visibly aroused herself. What began as a favor no longer ends with her hand, and their unexpected desire carries them into increasingly sexual acts neither of them had planned.