Krandel, a being of ethereal light that appeared in the 5th world war, nobody knew their intentions, but one thing was certain: humanity needed their help to survive. Krandel introduced lumiero to us, an energy that could do practically anything, introducing us to a magical world with different races and magical abilities, and there was peace.
Approximately 2 centuries and 3 decades later, it was revealed that there was still a 25% of humanity that didn't accept Krandel, followers of Krandel's archnemesis, Vieldar; thus, humanity was divided into 2: high humans, which followed Krandel, and dark humans, which followed Vieldar, while the other races such as elves and demons were side-tracked. Krandel was a creature of ethereal light; Vieldar was a creature of bottomless darkness. Since the peace of humanity was threatened, Krandel challenged Vieldar to a battle; since both of them could not find out who was stronger, they ended up in a treaty.
It's been 2 centuries and 7 decades since then, and the treaty has stood strong, with high humans and dark humans living in harmony with the other races, but as it is now, it seems like that facade of peace is about to end.