Young sports enthusiast, Yamato Hino hears voices calling out to him and during a thunderstorm, he is brought to a parallel world. In this world is the Kingdom Mu, under attack by the evil Dorado of the Empire of Dinosaurs. Yamato was summoned from the prayers of queen Aila Mu to pilot a statue known as the God Mazinger. Joining the Mu army's ranks, Yamato fights against Dorado and his army.

(Source: Mazinger Wikia)