Eternal Arcadia: Kuuzoku Weiss Sanjou!

Thousands of years before the events of Skies of Arcadia, six civilizations coexisted on floating continents in the titular skies of Arcadia, a world with no apparent surface that is orbited by six moons of different colors. The civilizations, one of which existed for each moon, developed technologically to the point where each created a Gigas, a...