I know of four from my world, personally! One of them prefers to keep his identity a secret, though. And one other from a different world, but I doubt he's from the same one as you.
I've also met someone claiming to be from his world's hell, though I couldn't say if he was an actual demon or not.
sender: Shikanoin Heizou
I've also met someone claiming to be from his world's hell, though I couldn't say if he was an actual demon or not.
Helpful~?