100 years ago there was a horrible world war that encompassed the land. One of the nations, in an attempt to win the war single-handedly, not only opened a portal to another theoretical world, but harnessed its power into a weapon. Random dimensional portals opened, letting through terrible monsters that slaughtered thousands, and the portals’ energy warped the land and mutated normal animals into monsters.
It also mutated the human race, rendering them frail and incapable of producing offspring for over 40 years. The war continued until the human race was decimated by casualties or by being eaten and killed by the various monsters. The best and brightest of human kind were stuck in a shuttle and sent to Cloud Nation, a floating continent, where they developed genetic advances that allowed them to cure themselves of the breeding pathogens before everyone else that lived below. It also gave them insight into the monsters that plagued the world.
The regular people left behind made the best of their lives, living off the scraps sent down from Cloud Nation. Some areas are still rampaged by rogue militia groups or street gangs not scared to shed blood, but he majority of the people have agreed that violence between humans is a bad idea, especially with such a small population that is still attempting to reach 1/100 of what it used to be. Instead, the people use special collars to control the monsters, settling their differences by seeing who can train their monsters the best. The first collars were just another piece of rubbish dropped from above, but the technology has spread and each of the remaining nations has their own tweaked gloves to interface with the collars.
Now, after 100 years of silence, Cloud Nation has invited the best trainers in each nation to compete for the world monster trainer trophy. Not only is winning a trophy worth more than the average person’s entire estate a huge deal, but the chance to see Cloud Nation with your own eyes is too much to pass up.