When their parents remarried, Rika and Yuichi suddenly became brother and sister. Rika is shy and quiet, but she's actually a sadist. Yuichi intuitively believes Rika is a masochist, Rika he trains her to be his personal toy. She gives him a footjob with a panty shot in the house where their parents are. She sneaks a blowjob when her mother isn't looking. She sits on his face and makes him lick it as a masturbation toy. Then she calls her best friend over to tease her brother, and shows him the sex she has with her boyfriend!