Set in Tokyo, the story is about the end of mankind, which takes the form of a final battle between two close friends above the sprawling city. They learn of their great destiny from two opposing oracles (sisters -- one with big breasts, the other with a small mouth), who enter their dreams and implore them to accept their unfortunate roles. They submit. One joins the Dragon of the Earth (who want to destroy mankind), the other joins the Dragon of Heaven (who want to save mankind), and their big battle happens on the Tokyo Tower.
What's interesting about this story is that those who want to destroy mankind actually have a better argument for doing so than those who want to save humanity. The Dragons of the Earth, who are not bad people, state that man has wrecked the environment to such an extent that if Earth hopes to survive, man has to be exterminated. The Dragons of Heaven, on the other hand, don't have a valid reason for saving humans, other than they are doing it for their friends, for their kids, and for the hell of it. The fact that there are no good guys or bad guys in X reveals a truth about anime in general: One doesn't watch it for the story, but for the technical wonders. And despite some amazing accomplishments -- truly, no other art can capture the spectacle of big cities with the intensity and detail of Japanese anime -- those wonders just aren't enough.