Mazinger Z vs. The Great General of Darkness (1974)

Kouji and his friends have defeated Dr. Hell and are now enjoying a break, but suddenly a strange prophet appears and warns everyone of an oncoming danger, mechanical beasts, never seen before, start appearing all around the world wreaking havoc. It's up to Kouji and his Mazinger Z to stand up to this threat but it seems he is vastly outnumbered, and outmatched.