A long time ago people lived peacefully; they lived and died, they improved, explored, and discovered, but they wanted more. 
They became greedy, they wanted to be kings and rule the world. 
Unnecessary fights, murders, wars... Gods decided to stop this. 
At the end of every year, during December, they opened gates to Hell so demons could freely punish, torture and kill. 
The world began to become part of hell. People stopped fighting each other, they united, but that was not enough to defend themselves. 
One demon was different, much stronger than everyone else, who once was a man, an assassin, who killed others to live, which in turn landed him in Hell. 
But after some time in Hell, he had grown weary and regretted his past life and wanted to help the humans. 
He became a guardian, and at the end of each year he fought off the demons. 
The people called him Guardian of December. 
The Devil noticed that his armies were being slain, so he offered a deal: no demon will ever come to Earth again, 
but the Guardian of December must return to hell. 
The people were saved and the guardian's soul was trapped in hell once again. 
After a year, when the gates of Hell were opened again, the people were hoping that no demons would come out again... 
But the Devil broke his deal and demons started crawling out...