I like this idea it reminds me of the Marvel Civil War stuff. I think we should play on the side of the Guild but a separatist group could become evident later on.

The one thing I wanna say is maybe a bit more lenient on the branding. Not exactly the forehead but on the body maybe? It'd say a lot about a character when it comes to where they were branded. 

Also maybe if Yokai begin devouring humans they transform into something evil and way more dangerous? Kind of like a sickness or mental issue thing going on where they become tainted. Another thing the Guild could have to deal with that would be a lot more dangerous than just other Yokai.

I also would want to be strict Oriental Influence, there's a lot of stuff if you go looking into it. Kinda sick of the same Cleric/Knight/Rogue types.