Sayounara Ryuusei, Konnichiwa Jinsei

Synopsis:

The oldest and most powerful dragon, having lived through endless ages, allowed himself to be slain by a Hero. But instead of eternal rest, he found himself reborn as Dran, a simple villager on the frontier. Tending fields, hunting in the forest, and enjoying a peaceful life brought him a joy he had never known as a dragon. However, one day while patrolling the woods near his village, Dran comes face-to-face with a formidable demon army threatening the calm he’s come to cherish.