Anh, the younger brother, thinks he's alone in the house, but his sister has other plans. She watches him through the crack in the door as he strokes his cock, his eyes closed, lost in his own world. Her curiosity piqued, she slips into the room, her heart pounding in her chest. Anh, startled, freezes, but his sister's hungry gaze on his cock is too much to resist. He continues to stroke, his pace quickening as she watches, her own body responding to the sight of her brother's pleasure.