Keeper names don't really come off as Japanese-esque to me. I can maybe see how one might consider such, but... Keeper and Seeker Miqo'te names we've seen given to NPCs (or that have been spewed from the in-game name gen) seem closer to the Bengali language to me. Either that or, as Berrod said, possibly an African language.
I can't say much on the migration bit as I think we know too little to make any solid guesses, honestly. But Zero makes a good point about how we have ONLY seen Hyur Domans plus Yugiri thus far.
I can't say much on the migration bit as I think we know too little to make any solid guesses, honestly. But Zero makes a good point about how we have ONLY seen Hyur Domans plus Yugiri thus far.