Mujina as a character race (5e Changeling from Eberron tweaked and adapted for Mystara)
by Marc SaindonThere are different versions of the Mujina, one of which is a badger version (which overlaps a bit with the Tanuki), and there is the hawaiian faceless version of the supernatural creature (which probably inspired the BECMI entry in the RC Monsters section). Since Yasuko is so far south, I'll take the Hawaiian interpretation of the creature.
So lore-wise, a Mujina would count as a Yokai (fey) that at times crossed over from Horai (Good Kingdom) to Yasuko. At first, contact was hostile, and the few surviving Mujina would travel as Rogues and identity usurpers.
Eventually, the Rakastas caught on, and in their great "cultural pact" agreed to provide protection and rights to the Mujina, under various conditions, one of which was a public licensed identity, as they don't have a personal individual one. This is a bit like Pokémon, where every town has its own Officer Jenny and a Nurse Joy (this was done for budget reasons, but with fridge logic, you suspect cloning and social conditioning). So in Yasuko, a family of Mujina could hold the public license to play one role: the shop runs 24 hours/days a week with "Mister Fuji" overseeing it, although several "Fujis" split shifts and share the same appearance while on duty. The humans of Yasuko have adapted to this, although foreigners will find this unsettling ("after dating Sakura last night, now it's like she doesn't remember me at all!").
Not all Mujina adhere to these rules, so a few "wild ones" are still on the fringes, causing trouble.
Notes:
Mujina
Changeling
Godai (Japanese philosophy)
(Image from: https://devmedia.discovernikkei.org/articles/3863/Painting_by_Edwin_Ushiro.jpg)