You know, there are New Guineans living today who can remember the first time they saw metal. Conquering the region and suppressing revolt would not have been much trouble for the Japanese, especially in light of existing tribal rivalries. After that, the collaborators would start pouring in, as well as the invisible agents of imperialism, the anthropologists. Just like the US with the Indians, the British in Africa, or the Japanese themselves in Taiwan, ethnographers and linguists will come in and start studying native cultures and languages and would very soon begin producing handy reports for government perusal. Sure, many would say they're not doing it to aid imperialism, but the effect is the same anyway.
Anyway, it's my understanding that near the end, Japanese imperialists were taking tentative steps towards defining Japanese-ness not by ethnicity, but by citizenship. Yes, they were going for multiculturalism. So a Japanese person might be from the Home Islands or Taiwan or New Guinea, but they're all Japanese. Many historians believe it was just half-assed rhetoric, though. This one academic blog I follow makes reference to the subject (see footnote 4), though I remember seeing a more-detailed article about the subject somewhere.
There's also some interesting points about how the Japanese were trying to "Japanize" Korea. In other modern empires we find male occupiers taking local women as wives, but in Japanese Korea we find a lot of mixed marriages are between Japanese women and Korean men. This comes from Japanese ideas about the household. You see, mothers are seen as the ultimate influence in raising children, therefore the best way to make Koreans Japanese is to have the next generation raised by Japanese mothers. Many Koreans saw the union as advantageous since for them Japan was epitome of modernity. A lot of the men were intellectuals--again, it was about being progressive and modern--and quite a few had both Korean and Japanese wives.
It would have been interesting to see how this might have played out in Australia or Seattle. From the perspective of the white husbands, they would have been asserting dominance over their conquerors, while from the perspective of the Japanese wives, they would have been civilizing the next generation.
