Hmmm...digging a little more deeply into this (as in, I actually checked the wiki and didn't just go from memory), I note that there's actually an Otomo Regent in there, who (to me) wouldn't count as a Hantei (though I obviously did blithely count him as one in the past and the numbering just stuck in my mind.) This means, since the numbering started with Hantei X, then working backwards from that (and ignoring the Otomo guy), the Kami Hantei would HAVE to be Hantei I...which means that the statement in the book, "thirty nine generations of Hantei", WOULD seem to suggest it's the current Hantei's successor. So...huh.
Edited by DGLaderoute