One day, Fumina accidentally catches her son masturbating. Seeing her young, throbbing son's cock, she feels her pussy getting wet and her heart racing. Unable to contain her arousal, she returns to her room and begins pleasuring herself. Just then, her son opens the door and discovers her masturbating. Overcome with excitement, he begs his mother to let him have sex with her—just this once. Yielding to his plea, she opens up her ass, and a new relationship begins between them.