Even through the curtains and partition, you could hear the older sister's moans, leading to the aroused girl being repeatedly penetrated. (NHDTC-233)

Two sisters, very close, shared a room separated by a curtain. Whenever the older sister's boyfriend stayed overnight, the younger sister, living next door, had to suppress the noise during sex. The younger sister found solace in the erotic moans coming from behind the curtain, secretly masturbating. When discovered, the boyfriend ejaculated inside the younger sister's vagina while the older sister slept, causing her to reach orgasm multiple times. Shortly after, the younger sister surprisingly requested unprotected intercourse.