Little Devils

Little Devils (魔王兄弟, Maou Kyoudai) is a manga by Uuumi. It began its serialization on the Comic Ryu Web website in August 2016. Seven Seas has licensed it for English release.

Plot
After the demon king is defeated by the Hero, he splits into twelve young demons. The Hero, Byron, is now tasked with raising the twelve demon brothers into paragons of virtue, for the sake of peace across the land.

Official
Official English site