Some of these 
categories were hereditary, others not.  Their treatment was pretty rotten, 
although I don't know if it fits into your fanfic or not. 

 Burakumin.  As I recall it was a situational condition until the 
extablishment of the Tokugawa Shogunate.  This was one of the most stable 
periods in Japans history, however one aspect of that stability was that ALL 
occupations became hereditary.  Even after the Meiji Restoration eliminated 
this, there was a great deal of sentament opposing leting the Burakumin do 
anything but their old heriditary jobs.  To this day there's a strong prejudice 
against anyone who's discovered to have Burakumin ancestry.
 Anyways remember that it's seldom a religion that causes problems, it's 
the organisation built around the religion that can make life hell for some 
people.
--------------------------------------------------------------------------------

Right.  But there was also another group (the word "eta" keeps springing to mind
and I'm not sure why) who were outcastes even before the Tokugawa era.

The specific jobs that were problematic were anything to do with death, since 
Shinto considers death to be a defilement.  So tanners, butchers, etc were all 
in this category.  (This category wasn't hereditary before the bakufu, IIRC).  
As you can see, their status arose directly from the shinto religion.

But there was another group who were just outcastes, and it didn't matter what 
they did; they'd still have been outcastes.

Gavin