Legend of The Galactic Heroes starts off in IC (Imperial Calendar) 487, with the Galactic Empire, mostly based on the 19th Century Prussian Kingdom with an authoritarian system, embroiled in an endless war against the Free Planets Alliance, an inherently democratic state. A third, smaller power, the Phezzan Dominion, although nominally attached to the Empire, managed to stay neutral as a buffer zone between the Empire and the Alliance.

On top of all of this, the cult of "Terraism", a cult that advocates for a return to the now decayed and abandoned planet Earth, orchestrates attacks and acts that provoke instability in both states.

With this complicated web of politics, alliances and moral discussions full into play, Reinhard von Müsel, an Admiral, schemes to rise in power within the empire, while Yang Wen-Li, a pragmatic man that originally wanted to become a historian and live an easy life, finds himself rising through the ranks of the Alliance while trying to deal with opponents from within and without that would rather have him off the picture...