I Am Learning to be a Succubus?

Since turning from a scholarly older brother to a petite younger sister, "Lili" is trying to adjust to her new life as a succubus with little success. While her body becomes more feminine, the more she loses her original self, and she's gotta do something! What's not helping is that her new big sister says the only way for her to obtain her old abilities is to feed as a succubus. With not much else of a choice, Lili might as well give this a shot!