Ryoumin 0-nin Start no Henkyou Ryoushu-sama

After spending decades fighting in war, Dias finally returns home as a celebrated hero. As a reward for his service, he is given his own land to rule. However, instead of receiving a rich kingdom, he finds nothing but endless grassland with no people. 

After spending so many years in war, Dias has no idea how to build or manage a land. When he lost his home, he met Alna, a mysterious horned girl who teaches him how to manage a land. With the help of Alna, Dias begins his journey to turning an empty wasteland into a village. Along his journey, he discovers new allies, uncovers hidden truths, and learns how to build a homeland.