Mashin Hero Wataru (1988)

A series set in a fantasy world, primarily inspired by RPG video games. A mystical dragon transports the 9-year-old boy Wataru Ikusabe to the pyramid-shaped magical realm of Soukaizan. Wataru learns that he is the destined savior who has to rescue this world from a demonic ruler. In order to do so, he must cross several levels of the pyramid and defeat the villainous rulers of each level. On the way, Wataru befriends several local heroes.