Have you heard of a game called Blood Will Tell? There's a nine-tailed fox there too. Eh, just wanting to use that once, because there are so many demons in that game.
Um, I think the reason they stop at nine is, now I'm not sure but maybe, because nine is an unholy, or holy number. Or maybe they never saw a twelve-tailed fox. xD There are two types of kitsune. The myobu, who are celestial foxes, and benevolent, and the nogitsune, or field foxes, who are the mischievous or malicious ones. As for why it can only have nine tales, I cannot say. Sorry.
Another reference to Japanese spirits and demons besides Pokemon, is Digimon.
Oh. Amikiri is the name of the net-cutting spirit. Not demon. My bad.
And were you talking about a living ghost earlier?