Mike Noakes wrote:

	Second:
	Yokho - 108th (?) demon-hunting descendant, current in a long 
line of mamono slayers (BTW, what's the diff. between a youma and a 
mamono?).  Is it ever said who was the first hunter?  Who established the 
line?  Why?  Are there other family lines of demon hunters?  A good page 
where I can read up on this stuff?

In Devil Hunter Yohko 5, it was revealed that demons invaded the Earth, and
"Just as our world was about to become a second Hell, a girl appeared who
could stand against them.  Her name was Haruka... Haruka Mano." From this
information, my *GUESS* is that Haruka was sent by Heaven to defeat the
demons.  As for other devil hunter lines, I don't think it's likely, but if
it suits your story, go ahead (Azusa's family is one possibility.  Also, in
the DHY/Ranma crossover, the Saotomes are devil hunters)