Regarding races, it is a bit trickier.
From 1E we have Hengeyokai, Spirit Folk, and Korobokuru. From 3E OA we add Vanara and Nezumi (although Nezumi are more specific to Rokugan than anything in any Asian mythology or legends I've read).
Korobokuru could be easily adapted as a Dwarf or Halfling subrace, I'd think.
Genasi might work as a stand-in for Spirit Folk. Keep the mechanics, switch out the flavor to make it more like the tropes of Japanese fairy tales (old infertile couple gifted with magical child...Momotaro, Kaguya-hime, Kintaro, Issun-boshi, etc.)
Hengeyokai would probably need a dedicated home brew race like the one linked above. Vanara as well (and ditto on the above link...plus shout to Yazirians! Or whatever they were called in Spelljammer).
If someone wanted to do it themselves instead of using the above linked races, the Eberron Shifter might serve as a good template for work on Hengeyokai, at least for their human/hybrid forms. Nezumi (if you wanted to keep them) could probably be modified from the goblin PC race.
Humans, if I were doing this, would have to be the variant human, with an extra skill and feat but only +1 to two ability scores. That's just my preference, though. No reason why anyone else should feel bound by that.