In the dimly lit bathroom, Patito San's curious eyes widen as he spots his sister, a delicate silhouette through the frosted glass. Intrigued, he enters, finding her naked, her body glistening under the harsh fluorescent light. She's caught off guard, her hand still between her thighs, fingers slick with her arousal. His gaze lingers on her full breasts, the dark nipples hardening under his intense stare. She shudders, whether from embarrassment or excitement, he can't tell. Their eyes meet, and a silent understanding passes between them.