Japan isn't any farther north than the US. The northernmost island, Hokkaido, is indeed pretty far north (I think roughly the same latitude as Oregon, and also southern France), but most of the rest is quite a bit farther south. Tokyo (where most travelers visit, and 1/4-1/3 of the population lives) is I think roughly the same latitude as North Carolina, and is quite warm. Japan is nowhere near as far north as Alaska, if that's what you're thinking, and not even nearly as far north as much of Europe.