Sexually harassing the nipples of his shy, innocent girlfriend's younger sister causes her to experience sensitive, premature ejaculation and continuous nipple orgasms. (Kuramoto Sumire LULU-126)

The girlfriend's younger sister, whom he met for the first time, was an introverted and shy beauty, unlike his outgoing and experienced girlfriend. The innocent and naive younger sister, who knew nothing about men, developed an interest in him...