A mother and son enter a mixed-gender hot spring. The mother's body, seen after a long time, is incredibly sexy, and the son's cock gets hard involuntarily. The mother gently soothes her son's erection. The son's excitement reaches its peak, and despite knowing it's wrong, he can't help but suck on his mother's breasts. The mother, unable to resist her son's advances, surrenders to his touch. What happens next between them...?