Although, I suppose if the rest of China has gone hard-line Red, the Japanese might find enough people afraid for their necks in the case of a Red takeover to run Manchuria (Greater or otherwise) as a puppet regime, although I remain dubious as to it's profitability or long-term stability. Korea, meh. There appears to have been more collaboration than the standard patriotic mythos has it (an awful lot of the ROK early leadership were, shall we say, compromised) but Japanese colonial policy was pretty brutal and unlikely to produce the sort of economic boom that OTL Korea had.
Bruce
Sure; but a poorer Korea might still serve nicely as part of the Empire.
Perhaps they could give the Republic of Korea independence in the 50s, as part of an anticommunist alliance?