Because he has the airplane, he can very easily save Korea from Japanese occupation. He has 100% air superiority. Just manually dropping bombs overhead is enough to send them packing. Or, doing a bomb run to their capitol. That would definitely make them recall their troops. Having the airplane inhand would also bring America to your side, as well. At bare minimum, he could get the Japanese troops recalled.
Because he has the airplane, he can very easily save Korea from Japanese occupation. He has 100% air superiority. Just manually dropping bombs overhead is enough to send them packing. Or, doing a bomb run to their capitol. That would definitely make them recall their troops. Having the airplane inhand would also bring America to your side, as well. At bare minimum, he could get the Japanese troops recalled.