since the poster doesn't seem to know much about airlines, I'll post this to be nice:
1) "Regional" airlines--whether wholly owned by a major airline, or merely contracted out by a major airline to do regional flying, don't typically operate outside of North/Central America and the Carribbean. Even the aforementioned Chinese op with Mesa is pretty much a separate company. Part of the reason for this is that a CRJ-200 might not make it too far with a full load of passengers. Unless you used half as many pax, got a special flight permit for supplemental fuel tanks, and gave each pax a jerry can full of jet fuel instead of peanuts and soft drinks.
2) NWA "mainline" would be who actually flies into Japan from the US (and back).
3) You could theoretically work for an NWA regional carrier (in the US), and commute from Japan once you held a line...but you would spend most, if not all of your days off standing by for flights and trying to sleep crammed into economy class on 10 hour long flights.
Hope that helps. By the way--ALL YOUR BASE ARE BELONG TO US!!!!!!!!!!!!!!!!!!!!!