That was a good find!
That was awesome.
There were three things that bothered me though -
-- The first was that the beast was named Mononoke, which was used later by Miyazaki in Princess Mononoke - I'd prefer to think Miyazaki wouldn't recycle like that, but I understand why he might of done that.
Mononoke literally translates out to "person of temper/nature." I think Miyazaki cares more that the names reflect character rather than be completely original. The name is quite fitting in both cases.

I think I've seen that wheel thing he rides on in other Ghibli movies. Totoro, perhaps?