Mijo (Pronounced "Me-Joe"). The city that makes up the entirety of the human race. Due to overpopulation, Humanity decided to unionise and create a megacity, which connects all seven continents, and modern islands. Although the different Arks (which are the different cultures) have different names for the city, the universal name is Mijo, and it holds the rest of humanity as a home after the catastrophic "Re: BiRtH".
All the districts are separated by walls that always have some border patrol and these walls are always heavily guarded by the angel-dressed military-police of the government. Although there are always official ways to get in, there is of course the illegal and much cheaper option, which is to either make your own hole or to go through another common criminal route, but these are often controlled by criminal kingpins that are hard to buy. So which way do you wish to go? The protected but uncomfortable guard route or the quicker but unsafe criminal route? One will be wise for their own decision
The people get around from one distant Ark to another by underground Hyper train, able to go through the earth directly and go to said Ark. Some of the districts seem to come out of a cyberpunk movie, with the artificial sky always being dark and some of the only light sources are the neon lights that urge their citizens to either buy a gun, cybernetic upgrade or a house. Other cities seem more normal however, and with the sheer amount of them, along with the people, it makes sense for their to be such a large amount of them. These "Arks" are the different cities and range from the size of an old PrE: BiRtH city called "New York" to another PrE: BiRtH city called "Tokyo".
The outskirts of Mijo are what is remained of the old apocalyptic world that modern society left behind, but due to government regulations, the civilions are kept hidden from the truth of the outskirts. But lucky for you, dear reader, we are not the people, are we? No, we are the observers of this world. So, what remains on the outskirts are... Oh, you thought it was that easy? I pity thee. No one truely knows what the outskirts are, even those head of the government. Although they do send soldiers out there to discover and fight the strange, feral monsters out there (Products of the "ArSenIUm" Radiation a popular theory is), but even their knowledge is limited. The outskirts is an unforgiving and dangerous, not suitable for even the most well prepared and battle hardened soldier.
"The Re: BiRtH. What is it?" You may ask, and let me tell you, it is the most wildest of stories. In the year 2034, humanity realises that after the drastic measures of its actions, it has destroyed the planet past saving, and multiple instances of riots, political assassinations and other heinous acts committed only by the most darkest of mans soul was driving the world into madness and the remaining political higher-ups put together a new government named "The Advocates for Humanity" (AFH for short) that start to put out their own solution; purging humanity except those of exceptional intelligence, leadership or strength. Starting in 2049, when the AFH has gathered all the people it has needed, the AFH start to send out their own soldiers in order to retake the land that was once of peace and also to recruit more of populace to join the "Ark of Humanity" as they call it. Despite this organisation and recruitment, the soldiers are always fought back to by either savages who only wish to kill or those who want their supplies. After almost 8 years of enduring defeat after defeat, the AFH has created a new. toxic to only humans substance called "ArsEnIUM". This substance kills or mutates humans (Depending on the dosage) and the AFH has put these into bombs to be launched across the globe, despite multiple attacks done on them. These were the bombs that activated the 1000 year destruction and purge of humanity called the Re: BiRtH. The Re: BiRtH gave birth to not only humanities near extinction (Including that of the AFH as they had some bombs detonate near them and wipe them all out. An Ironic death for a ruthless goal), but the monsters that inhibit the world to this day. Not much has bene known about what events that transpired during the 1000 years before Mijo was declared, but we do know one thing, and it is that their is the slimmest possibility that someone, or a group of people, still live out there. We just haven't seen them yet.