The Eusan Nation is a state in the style of communist regimes of the real-world 20th century, primarily the German Democratic Republic. Its government is authoritarian, and it practices extensive propaganda, censorship, and repression.

The Nation is known for its military history. It was founded by the Great Revolutionary and her Daughter and fought for its independence from the Eusan Empire during the Revolution. It is now locked in a war with the Empire and seeks to take control of the planets still under the Empire's control. After the death of the Eusan Empire's leader, the Grand Empress, the Great Revolutionary, and the other founders of the Nation rose up in a civil war against the Empire. The Nation took over Rotfront, Leng, and Heimat, the latter becoming their capital.

The Nation relies on Replikas (Biomechanical humanoids/cyborgs), which it uses as workhorses. Although artificial, Replikas often stand higher on the societal ladder than the humans they work with and oversee. The higher-ranking Replika models, hold authority over other Replikas as well. Citizens are used as resources and tools to be exploited and, sometimes, discarded in the pursuit of political objectives. Displays of individuality and interest in the arts are disapproved of. Military service is compulsory.