Strahl Demokratische Republik

The Strahl (also sometimes referred to as "Shutoral", the phonetic pronunciation of the German word) are akin to the Axis powers in World War II. Maschinen Krieger is, after all, a loose interpretation of World War II as played out in the future that is the late 2800s. Information is sketchy and sometimes contradictory, as we have to sometimes rely on off-kilter translations from the Japanese.

Apparently the backstory chronicles the colonial uprising on Earth. The following was taken from Rob Brunskill's excellent site:

This war was the first armed conflict to take place on Earth since the depopulation early in the 29th century. Once the cradle of humanity, World War IV ravaged the planet and made it uninhabitable. By 2855 the planet was safe enough to begin terraforming and planning for colonization. What was once humanity's only home became a backwater colonial planet, and a haven for criminals, mercenaries, persecuted, migrants, farmers, laborers, and many more seeking refuge. Earth was largely ignored by the Galactic Federation until 2877, when control of the planet was given to the Strahl Demokratische Republik.

The resulting war that soon followed between the SDR and the rebel Earth forces—commonly known as the Mercenary Army—fielded an incredible array of new technology. The armored fighting suit, artificial intelligence, and antigravity propulsion all made their first mainstream military appearance.