With the advice of her brother, the plain step-sister who nobody paid any attention to transforms into a beautiful woman who everyone turns their heads to see! The brother can't help but confess his feelings to his step-sister as she learns how to put on makeup and gradually becomes more beautiful, but she refuses because they are 'siblings'. The two of them promise to just do a bare thigh job, saying, "You don't have to put it in, just rub it together..." but... the step-sister's pussy is so slippery that he just inserts it! Even though they try to refuse, the sexual desire of the two young people who have crossed the line once can't be stopped and they end up cumming inside each other. The two of them continue to do it after that...