[Reikou]

Don't Youkai come from their own little dimension? In that case there's no problem with the same ones being available.

Also, I believe some of the simpler classes would also be good to go after a small flavor text and skill desc update, ex: Black knights not referencing the black wind but something else, like a magical aura of some sort or special stance and having different origins.

 But when it comes to unique-er ones like engineer, firebirds etc I'm not so sure.



As for races. . . Blessed ones, besides maybe Elfs, are probably a no-no since the place is supposed to be untouched by those who created said races in the first place, isn't it?