There are other Youkai, but listed are the ones that have either large populations or that are known across every island. Some Youkai I haven't put much thought into, so feel free to pm me if you want to talk about ideas for one.  

As for half races there are, including half races from outside of the island, though young half kitsune are very rare to see outside of the Kitsune homeland. And don't often leave their parents for a while.  


Half Oni it depends on both their clan and how they look.  Ones that look like humans can normally along just fine, though some clans with heavy oni problems still distrust and dislike them.  Those that look more like Oni often face much more discrimination and if their parent is poor or not very respected they are often kicked out of their clan.  Clans like Shima don't kick them out but many people still are uneasy and only accept them because tradition/Lord Shima says they should.

Oni tend to assume half Oni are weak, but once one proves him/herself then they get the same respect as anyone else. As such Half Oni more often live with Oni tribes.