Rather than having a war between the colonies and the Earth, a fighting tournament is held. Called the Gundam Fight, it is held once every four years by the United Colonies Federation. Each country would send its own representative, that would pilot a Gundam, and the Gundams would then fight on the Earth until only one is left, and that Gundam's nation will then be able to obtain sovereign rights over all the nations, until another nation wins in the next Gundam Fight. This series is set in Future Century (FC) 60, during the 13th Gundam Fight and it focuses on the Neo Japan Gundam Fighter Domon Kasshu, who is in the fight as much to win as well as fulfill his own mission of tracking down his brother who had stolen a mysterious Gundam; the Devil Gundam from the Neo-Japan government.

(Source: Wikipedia)