You know, I got to thinking while I was insanely bored at work today, more about Ukoku/Nii's hair. (And imporant topic for thought.)
I originally submitted that Nii's hair was always this long, and simply combed back. But let's say, for sake of argument, that it wasn't -- that in his appearance as Ukoku, it was indeed longer.
If you compare it to what's happened previously... who are the characters who've had mysterious hair-growth in the blink of an eye? Goku, transforming to youkai form. Hakkai, transforming to youkai form. Catch my drift?
(I can't think of any other hair-specific changes at the moment, but it still illustrates my point.)
I'm not saying that Nii's a youkai, no, not that. However, it's his job (or hobby, perhaps) to "combine human science with youkai magic". Maybe he, as Nii, is wearing some sort of limiter, becuase he's somehow used his knoweldge to give himself more power? Or maybe a limiter to simply hide his power as a Sanzo?
Or maybe I shouldn't be so sure in saying he's not a youkai....?
Or is this a stupid theory?