Tomoyuki Aida and Rinka Momose are in a cousin relationship. Rinka, who came to Tokyo to go on to school, will be taken care of by her relatives, the Aida family, until a room is found. Then, the two of us reunited after an interval of three years, Tomoyuki the same lewd boy. Rinka has matured as a woman with her physical and mental growth. What changed by Tomoyuki from three years ago was his knowledge of sex and curiosity. The magical hand of such a lewd boy, Tomoyuki dyes pure Rinka into a woman.