My father, brother, and sister live in an apartment complex on the outskirts of Tokyo. My younger sister (21) went to college and supported the family as a substitute for her mother. My brother is a children's room uncle (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 a secret called "systemic erogenous zone", felt good even though she knew that sexual intercourse with her brother was not good.