Youseiou

Sickly high school student Taka journeys to Hokkaido in search of a magical cure and falls in with Khoo Fu-Ling, the king of the fairies. Ninfidia, the land of the fairies, is under attack from the evil Queen Mab, and Taka must save it.

Incorporates elements of legends of King Arthur and the Knights of the Round Table, as well as scraps of Celtic, Greek, and Ainu myth.

(Source: Animevice)