Mashin Hero Wataru: A Story At An Endless Time(1993)

Mashin Eiyuuden Wataru: Owarinaki Toki no Monogatari

The story is about a 9-year-old boy named Wataru Ikusabe who is magically transported to a magical realm of the gods called Sokaizan which he is supposed to save. He also befriends many of the Soukaizan natives, and forms some very strong friendship bonds.

(Source: Wikipedia)