Right before we were supposed to move in together, I had to stay at my girlfriend's place until our new apartment was ready. Her older sister, Rei, was a quiet type. At first glance, she seemed uptight, but at home, she was completely unreserved. Her H-cup breasts swayed without a bra, and her tight camisole revealed her pussy... I couldn't control my erection thinking it was getting dangerous, but then she started seducing me...!?