*SPOILERS* Manga

Is Seimei really alive or is it an imposter? My friends had me convinced at first that it was just someone pretending to be Seimei but the 7th manga made me believe it really is him.
I was thinking he has the same thing that everyone says Ritsuka has. Ya'know, the whole bipolar thing. Does anybody else have a theory. I know these boards are pretty dead but I'm really curious!!!

Nothing is foolproof to a sufficiently trained fool.