Laura's Mission and Promise
Laura had been sent to a planet where demons were present. That was of course thanks to her status as a possessed. Not only did Laura have an inherent disgust toward demons, but the skills she had gotten as a Demon Hunter worked best against them, dealing 50% more damage when targeting demonkind.
It was a planet that had a very low technological level, similar to the Iron Age of humanity back on Earth. When the game started, monsters poured out, but in low numbers as somehow demons also invaded the planet.
There were millions of demons that poured out of spatial gates, ranging from low-leveled, incredibly weak demons all the way to very powerful ones, the most powerful amongst them being Tier V.