I Became the Subject of My Girlfriend's NEET Sister's Masturbation Fantasies – Rin Hachimitsu My girlfriend's older sister is a shut-in. Even when I occasionally run into her at their house, we barely exchange greetings; she’s the quintessential antisocial type who glares at me with a sullen, heavy gaze. But one day, I accidentally witnessed her masturbating... Seeing the erotic body hidden beneath her plain clothes—her massive bust, slender waist, and voluptuous hips—gave me a rock-hard erection! From that day on, we ended up secretly engaging in mutual masturbation behind my girlfriend's back!