My girlfriend, who I live with, is wearing a chastity belt because she suspects me of cheating on her. One day, my girlfriend's older sister Rin comes to live with us for a week because she can't sleep due to construction noise... I happened to see Rin after taking a bath and I couldn't help but get an erection! Her chastity belt was discovered by her older sister, Rin. Just for fun, I played with her chastity belt... Like that, little devil sister Rin