Outo no Gakuen ni Kyouseirenkousareta Saikyou no Dragon Rider wa Chou ga Tsukuhodo Inakamono

Shimuru lives in the mountains with his companion Sorahime, a dragon. However, when he saves the royal platoon from a chimera, his life takes a turn. Having shown prominent strength, he is forcefully led to enroll at an elite academy in the royal capital. Furthermore, due to having been raised in a super backwater environment, Shimuru ends up frequently causing trouble. Source: MU