Yep, we appear to be in Hiroshima (or Nagasaki), in the midst of an atom bomb strike — a moment which has always had considerable meaning in X-Men lore. (The team is sometimes referred to as “Children of the Atom.” And by “sometimes,” I mean “it was the subtitle of a fighting game that you probably played in the mid-90s.” Ironically, Wolverine was only the second-best character in the game.)
We also see Wolverine push a young Japanese man down under cover, and hold the cover as the radiation blast fillets him. Director James Mangold has talked at length about how The Wolverine will confront the character’s immortality — it seems appropriate that the film will begin with the character surviving a nuclear blast. Side note: Am I crazy, or does this pit conjure up ambient Batman Begins memories?