What's the Name of That Book??? discussion

Book is about a secret group that fights invading demons. They have power from making "soul knots"(?) which gives them abilities and enhanced strength/speed.

First book starts with MC in hiding until demons attack his school. There's some ability they have that hides the demons from most people. MC goes to a training facility after.

The demons have different tiers with the lowest being animal intelligence and getting smarter at higher levels. I think they may have been enslaved to higher tiers?

Later books have the secret come out and the organization teams up with the world militaries.

Soulguard by Christopher Woods