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It's been 6 months since the L5 Campaign, the conflict that pitted humanity vs aliens with the whole earth sphere at stake; even thought at that time humanity joined forces as a whole and fought valiantly for it's survival, now that the true threat is gone the remains from old conflicts that have kept discord among people from even before the aliens arrived have started to resurface and thus the fight is far from over....
One night right before summer vacation, Daichi Manatsu, a second-year in high school, sees a weird round rainbow floating in the sky above Tanegashima and ventures there alone. He has seen this rainbow before. With the memories of his father's mysterious death and an encounter of a mysterious boy and girl, Daiji arrives on the island while the alarm of a building labeled "Earth Engine" is going off. Someone asks him if he's a captain, just as robotic intruders from Uranus called "Kiltgang" arrive. The battle around the shining stars is about to begin.
Set in the near-future, a little-understood form of matter known as "Mile One" allows a powerful and influential Japanese family, the Gowa, to produce a bipedal weapon which they refer to as a Tactical Armor (TA). At this time, a war breaks out between the US and the fictional Middle East country of Belgistan, much like the Gulf War. When US military forces attempt to seize the capital, they are systematically wiped out by what appear to be rival TAs. The Gowa Family seizes this opportunity to demonstrate their weapon system, and civilian pilot Yuushiro Gowa and the military squad to which he is attached are deployed to Belgistan. There, he meets rival TA pilot Miharu, with whom he seems to share a deep spiritual bond.
Duke Fleed is the sole survivor of an attack on the Vegan Empire; he defends his second home, the Earth, from the Vegan attack, together with the giant robot Grendizer.
Saiga Junki is a normal high school boy who tends to be a little apathetic in general but who does manage to get better than average grades. When his archaeologist father, who went to investigate some ruins, is found dead, the family travels to the excavation site where Junki meets a mysterious stranger who gives him a ‘gift’: an ancient artifact that his father left for him…
The greatly weakened Earth Federation comes under attack by the BESPA forces of the spaceborn Zanscare Empire; only the AEUG-like League Militaire stands in their way. The mass-produced Victory Gundam is the League Militaire's secret weapon against the invading BESPA.