Yoshikazu goes on a hot spring trip with his mother and relatives in place of his father. At first he is reluctant, but he can't take his eyes off his aunt Momose's voluptuous body... That night, while bathing alone, he accidentally gets an erection with her. Momose sees this and decides to release his overflowing sexual desire with him... Then, as she repeatedly urges him to ejaculate, Yoshikazu awakens to the pleasure of sex and devours her body whenever he gets the chance... At first he is confused by Yoshikazu's mad desire for him, but before he knows it he is responding to her and drowning in pleasure...