FNS-176 I Became the Masturbation Material for Her Busty, Shut-in Older Sister, Yatsumi Rin

My girlfriend’s older sister is a shut-in. Even when I occasionally see her at her house, we only exchange brief greetings, and she gives me a gloomy, suspicious look like the ultimate introvert. One day, I accidentally caught her in a private moment, and I was completely captivated by her surprisingly alluring figure, with a large bust, slim waist, and curvy hips. From that day on, we ended up sharing a secret, mutual private relationship behind my girlfriend’s back.