Against the backdrop of World War II, humans are also fighting against alien invaders. The Nazis and the Kanto Army are trying to steal alien technology to gain an advantage. Using the same alien technology to power giant robots, the Kishin Corps try to keep the Axis powers and the aliens in check.
The Nazi's have joined forces with alien invaders in a bid to conquer the world, and only the valian actions of a small band of heroes and their armored giants.