After six years of living together, his sex life with his girlfriend has cooled. Then her petite, baby-faced adult sister Rui comes to stay, casually flashing her round H-cup breasts beneath a loose shirt. She catches him staring, promises to keep it secret, presses against him, and points out his erection. With his girlfriend nearby, he gives in and devours her pale, irresistible tits, eager to lick, squeeze, and slide between them. Her addictive body makes him forget the consequences and risk everything for repeated sex.