Onizume's Pussies - Second Person POV, Onizume Corps Sibling Gaiden

A young man, Onizume, has a crush on his older sister, who is always cold and distant to him. One day, Onizume discovers a book that describes her own sexual encounters. When he begins to read it, he realizes that his sister is actually a sexual being, and that she has always been this way. With the help of his new book, Onizume learns to accept and love his sister for who she is.