Imouto sae Ireba Ii., also known as A Sister's All You Need, is a Japanese light novel series written by Yomi Hirasaka and illustrated by Kantoku. The story follows the life of Itsuki Hashima, a young novelist obsessed with little sisters, and his interactions with his friends and fellow writers. The series explores themes of creativity, relationships, and the struggles of the writing profession, while injecting humor and quirky character dynamics.