Kinda missed an opportunity with his backstory; I mean they just had a massive invasion, right?
If he was from Osaka, or Yokohama, or even Sapporo (well, maybe not Sapporo), they could have had "he uses the old names" along with "nobody is alive from that town."
Just a neat two-fer that they could've dropped for storytelling effect; also, would bring him further into the world.
But I like it, either way!