In the quiet of his room, Guto indulges in his desire, his big dick hard and ready. He strokes it slowly, imagining his sister's hands, her lips. His fantasy grows vivid, his cock leaking pre-cum. Suddenly, the door creaks open, and his sister walks in, startled. Guto freezes, cock in hand, as his sister's eyes widen, taking in the sight of his massive, pulsing erection.