the corporate government is basically an alliance of several corporate city-states, Kugayama City being just one of many, in the eastern district (so I guess it is around the Tokyo area). The central district is the oldest of the liberated/reclaimed regions and is managed not by corporations but by nation-states. The Corporate Government is technically under the umbrella of this super-confederation binding many regions/"districts", but it regularly stamps out nationalist sentiment in its domain, the eastern district, using methods up to and including the genocide of entire formerly-corporate cities seeking the establishment of a nation-state. A corporate city is further subdivided into a permanent underclass that receives lifespan-shortening rations and everyone else, and the underclass is further subdivided into low-class citizens and non-citizen slums, the latter of which provides the expendable mercenaries called Hunters. Far east of the eastern district is the front line, where that Drankham guy probably comes from. On the front line, the corporate government's military is more active and regularly deploys Humanoid Weapons which are basically non-sentient factory-produced Astartes in Terminator Armor except super agile and they can presumably fly (and you'll see more magical tech as the manga progresses meant only for use by these superweapons). All of this is explained in the web novel somewhere around this chapter.