Imouto sae Ireba Ii.

Imōto Sae Ireba Ii. (妹さえいればいい., lit. "If Only I Had A Younger Sister.") is a light novel series written by Yomi Hirasaka and illustrated by Kantoku. Shogakukan has published six novels since March 2015 under their Gagaga Bunko imprint. Two manga adaptations have been published by Shogakukan and Square Enix. An anime television series adaptation by Silver Link is set to premiere in October 2017.

Plot
This is the story about the daily life of a young siscon novelist, Itsuki Hashima with his perfect little sister Chihiro, the genius illustrator Nayuta Kani, his best friend Shirakawa Kyoto and some insane partners from his publishers.

Official
http://imotosae.com