A father, brother and sister who live in a housing complex on the outskirts of Tokyo. My sister (21) went to college and supported her family as a mother. My brother is an uncle in a children's room (32) who does not leave his parents' house. My sister has been processing her brother's sexual desire for a year. My sister, who had the secret of a "systemic erogenous zone," felt comfortable even though she knew that she couldn't have sexual intercourse with her brother.