Fairy King(1988)

Yousei Ou

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.
Based on a manga from 1978 by Ryoko Yamagishi.

(Source: AniDB)