Maou no Utsuwa

A world of magic and swords. Born into an aristocratic family of a large country, a boy with insufficient magic power bade farewell to his unlucky daily life. Because of his encounter with a Demon, his fate began to change. This destined meeting changed the boy's life, affected his surroundings, and soon after, shook the entire world.

(Source: Shousetsuka ni Narou, translated)