Dude or Dudette! Your story is awesome! Intriguing, beguiling and enchanting.
You have some minor but glaring grammatical errors. Do you have / want / need an editor?
Keep 'em coming!
I feel like this is selfish and lacking foresight (which I guess should be expected at his age). He mentioned how strong all the demons were so he could have pointed this out and used all those gates to train up more people. He can't fight all the demons if it comes to an all out war...
Mimbdy2