Now, I don't want to be an arrogant ass, but it's "youkai". American culture seems to like to take the "u" out of words and names after "o".
'Twas a grievous typo rather than blatant Americanized spelling error. I don't make a lot of the former, and I certainly don't make many of the latter, either.
Beyond the spelling, I only know a few actual Japanese "demon" (and other deity-type) names and characteristics: Oni, Tanuki, Tengu, Kappa, Onibaba, and obviously kitune [aka Kitsune, of course]. An online fellow artist and acquaintance professes knowledge in the matter of Youkai, hates Inuyasha (and most anime, I believe) and does wonderful, if trendy, artistic representations of a few.
I think you'd appreciate it, anyway.
Oh, and I always spaz if I see words like "colour" and "neighbour" without 'u'. That's fairly anal I