Tsuihou Majutsushi no Sonogo: Shintenchi de Hajimeru Slow Life

Lain, a reincarnated person, lives his life as an "Anti-Demon Aristocrat" who is responsible for defeating demons in the frontier. At the age of 15, his engagement to the princess, a privilege of the Anti-Demon Aristocrats, is supposed to be announced, but he is told to break the engagement and is also stripped of his status as a member of the anti-demon aristocracy.

Cast out not only by his country, but also by his adoptive-father, Lain leaves the royal capital and uses wind magic to fly through the air to a faraway village. For some reason, Lain decides to live in the village, where only young girls live, and works with the girls to strengthen the village, teach them magic, and enjoy the freedom he has never had before...

Lain has escaped his black environment and is enjoying the slow life, but Lain's power is affecting the world...!

(Source: Kodansha, translated)