In the future, some portion of the population develops the ability to spontaneously combust - and half the world's population dies in the "Great World Blaze." Most of the movie is set 30 years after that event. The people with the mutation are known as "The Burnish," and are subject to discrimination and oppression.
After quickly setting the scene, the movie really opens on the firefighting group "Burning Rescue" - who fly into action to put out fires started by Mad Burnish, a Burnish terrorist group. They use mecha and a variety of high tech innovations to fight both the fires and the Burnish terrorists.
After 25 minutes of nothing but action, all of which is insanely colourful, we slow down for a character introduction and a heavy-handed statement about the Burnish being human too, and showing the blatant oppression. We have about 20 minutes of plot and dialogue, and then the remainder of the movie is again taken up in outrageous, eye-searingly colourful action.
The resultant plot is, well ... both beyond ludicrous and simultaneously typical of Anime. Mecha fighting to save the world, mecha that grow to the size of small cities. Beings from another dimension. The true solution is harmony and understanding. Oh hell, they even have a mecha called "Deus X Machina," how much more blatant can you get? The artwork is beautiful, the plot is ridiculous beyond belief. I enjoyed it, but I don't think I'll watch it again (as far as I'm concerned, that's the real test).