In the Year F.C. (Future Century) 60, much of mankind inhabits space colonies which orbit the Earth. Dominance over the colonies is decided once every four years by a large tournament in which each nation sends a single representative to fight the others with a giant robot called a Gundam. Domon Kashuu is selected to represent Neo-Japan in one of these tournaments, but he fights less to ensure his nation's victory than to find his brother, who has been blamed for the deaths of Domon's parents and the disappearance of a very dangerous weapon, the Devil Gundam (Dark Gundam).

Three decades after the great war between the humans and the Zentradi, the U.N. government is developing new technologies to use in their transforming fighter aircraft by running tests on the colony planet Eden. Military test pilots and former childhood friends, loose cannon Isamu Alva Dyson and the Zentradi mixed race Guld Goa Bowman, are selected to each pilot a new aircraft (Shinsei Industries' YF-19 & General Galaxy's YF-21) for Project Super Nova, to choose the newest successor to the VF-11 Thunderbolt variable fighter which is currently still in use by the U.N. Spacy military forces. Their own personal grudges end up disrupting the tests, and begin to wreak havoc on the program.

Ultimate Muscle: The Kinnikuman Legacy, known in Japan as Kinnikuman II sei, is a manga and anime series made by Yoshinori Nakai and Takashi Shimada under the pen name Yudetamago. It is the sequel to the hit manga Kinnikuman that they started in 1979. The toy line of Kinnikuman was released in North America as M.U.S.C.L.E.. The name of Ultimate Muscle was chosen to connect the Americanized storyline of the M.U.S.C.L.E. toyline of the 1980s into the anime. Bandai also produced intermittently distributed toy tie-ins during the initial run of Ultimate Muscle.