FNS-176-lada · [LADA Decensored] I Became the Masturbation Material for My Girlfriend's Busty NEET Sister - Rin Hachimitsu

My girlfriend's older sister is a shut-in. Whenever I see her at her house, we barely exchange greetings, but she looks at me with these gloomy, judging eyes—the quintessential introvert. One day, I happened to witness her masturbating... and I got a full erection seeing the erotic body of this usually plain-dressed sister, with her massive tits, slim waist, and huge ass! From that day on, we started mutually masturbating in secret from my girlfriend!