I avoided speculation on the fate of Korea in my own offered scenarios. I believe the Koreans will be much disgruntled, but it is hard to judge how well the Japanese can coopt enough of them, even if only Stockholm Syndrome style, to retain a grip despite this resentment. Also, it is possible that the semi-liberal facade alliance with the British, or the form of authoritarianism combined with egalitarian rhetoric a Soviet alliance might foster in Tokyo, might give the Japanese overlord options in face-saving autonomy, even restoration of the old Korean royal dynasty or under Soviet example, a paper autonomy for a Korean People's Republic that in fact answers to Tokyo and its Zaibatsu corporate cartels at every turn--but wears the mask of Korean nominal leadership.
Another thing I fudged was what the hell happens in China if the Japanese aren't pressuring them. In my perception, the KMT was inherently weak, particularly under Chiang Kai-Shek's kleptocratic leadership making the regime a quarrelsome oligarchy of mutually jealous rich vested interests with damn little traction in the working classes and peasantry. OTL the Soviets gave the Chinese Communists a lot of aid, but a lot of that was to fight the Japanese. Without any of that aid, even with the Soviets aiding Chiang, it seems a push to me how much traction Mao can get. Arguably he is doomed, but even if the KMT, with Soviet and Japanese connivance in Chiang's extermination campaign, can wipe out the Maoist insurgency to the last man and woman, that just leaves a weak power vacuum that warlords can aspire to break loose in--Chiang has to herd these warlord cats into a pretence of Chinese unity. There is little funds or leadership left over for actual modernization, and meanwhile Chinese population continues to balloon. Something will give somewhere.
One reason I didn't tread on that territory was that it seems most likely to me at some point the reduced but still strong militarist factions in Tokyo see opportunities too good to resist, foreign allies be damned, in Manchuria and further afield, and there we are, OP conditions violated and Japan perhaps back on the same course as OTL.
So, after the Europe-only WWII, will Stalin hunkering down expel the Japanese, or seek to coopt them more deeply, perhaps orchestrating a Red revolution? Stalin and subsequent Kremlin leaders were actually very bad at that, preferring Communists who were loyal to revolutionaries with a free hand and fingers on the pulse of their actual nation. Mao, Ho Chi Minh and Fidel Castro prevailed despite Soviet "help" never because of it. Perhaps Stalin will back a coup that is quite frankly at odds with Soviet notions of proper Bolshevism. As noted, sociologically speaking, with proper leftist parties repressed, the closest thing that common workers and peasants had to political advocacy on their behalf was the essentially fascist route via the gung ho Army officers. Organizing them as Protectors of the Emperor, a sort of collective Shogunate, and refusing to institute Marxist class struggle language and instead making Japan a fascist arm with an ideology of partnership with the great Russian proletariat but with Japan remaining under Emperor and a essentially corporate order (but where the Zaibatsu can be overridden, or claim to have been overridden, by the Red officers in deep partnership with their handlers in Moscow.
Writing that it seems pretty improbable though; the powers that be in Japan would presumably rear up in resistance; in the context of a developing Cold War rift (it stays Cold for the same reasons as OTL; through most of the '50s the USA could declare war on the USSR without much risk of damage to the USA, but no one in the West wanted Europe turned into a charnel house yet again, and Stalin was always The Great Procrastinator) the "free" imperialists of Japan would turn to western support which the USA would grant, no questions asked, on the "they're sons of bitches but they're our sons of bitches" model applied so freely by the "Free World" leaders in the Third World in general.
I offered three scenarios in all of which Japan winds up allied to the Soviets in WWII, and explored possible ongoing relations with Japan a free actor; dismissing the possibility of post WWII conquest, even by Army officer subversion, of Japan as a whole, various forms of Soviet betrayal also apply. The Red Army will be quite strong in the postwar period and belated seizure of Korea, any White Russian regime under Japanese protection and alliance on the Pacific Coast, and conquest of or cooptation of China do seem more possible. Suppose that with the experience of a cordial relationship with Imperial Japan under their belts, the Soviets can coopt Chiang Kai-Shek, offering him a deal whereby they aid him in bringing the warlords to heel and in suppressing Chinese Communism, securing the KMT as permanent overlords of China, and give the RoC under Chiang industrial development aid? Could this work for Stalin? I considered them offering him the title of Emperor of China but that would be an unnecessary dissonance both with Leninism and KMT ideology I believe. President-Generalissmo For Life of the Republic of China is probably plenty good enough for Chiang! Stalin wants all Japan too but his schemes for that misfire, predictably, and he settles for overwhelming Korea and any defiant White rump state Japan has been protecting, and figures Japan with just Pacific islands including Taiwan is a weak opponent to be dealt with later. So Japan suddenly facing hostile Soviet power across the straits and lack of her long time access to northern resources turns to the victorious USA for help, which is granted. In a fun reversal, Chiang asserts the RoC claim to Taiwan but the Western powers back Japan and it holds as Japanese territory, now more Nipponified and loyal and integrated than ever. Cold War containment is now about building up Japan as an industrialized bastion much as OTL, but without South Korea--or conceivably pro-Japanese regime Koreans with IJA in retreat stand and hold the south more or less as OTL, with US and possibly other Western ally forces coming in to reinforce the front and an eventual cease fire and truce dividing Korea--but the South would remain Japanese, though Western liberal suasion might establish it as an autonomous region with Yankee forces being the major line of defense, as OTL.
The scenario should there have been a Japanese-protected White rump state that Stalin gobbles up forcefully post-war, or tries and fails to if enough Western allied resistance can reinforce the Japanese and domestic resistance there, offers some weird alternatives too. If a portion or all of it holds, repelling the Soviet takeover attempt (such resistance most likely to succeed if Stalin limits his stroke to a purported domestic pro-Bolshevik rising which might well implode before the Red Army can pour in to "defend" it) then along with a possible surviving South Korea under Japan, or instead of it, we have a Russian dissident state in Western as well as Japanese alliance, still impeding Soviet access to the Pacific and thus a huge Cold War hot spot. We'd expect it to be massively armed, unless perhaps Stalin negotiates a cease fire with treaty limits, in which case it is protected by permitted US and/or Japanese allied force in limited numbers forming a tripwire defense--the Red Army could walk over it any time but not without triggering WWIII. Considering that the USSR and USA face each other directly across the Bering strait another such front seems possible.
But what if the Reds manage to break in and take over fast enough, but not so fast that large numbers of the White regime there can't escape Soviet "justice" and make it to Japan for refuge? I think they would not stay in Japan--some might, because presumably ties have opened up between Japanese and White Russians since 1920, but most, having had their own homeland that is not Japanese, might emigrate elsewhere. A logical destination for them would be the US Territory of Alaska; in Cold War context they'd be made as welcome as Cuban refugees from Castro were OTL decades later, or Southeast Asians from Vietnam and Laos were. Unlike the Southeast Asian "boat people" if the Russian Whites descend on Alaska en masse they can quickly become the dominant ethnicity and bring numbers to catapult Alaska into US statehood, assuming the immigrant refugees accept US citizenship anyway, as I suspect they would. (In fact, if there were a post Russian Civil War White rump state on the northwest Pacific coast, I'd think considerable numbers of them would have previously emigrated to Alaska and other US destinations, so the arrival of huge numbers of them might find already re-Russified communities to settle in). Perhaps early Alaska statehood with a somewhat problematic (but welcomed because of their firm anti-Communist credentials) Russian-dominant society will promote offsetting this ethnic lopsidedness with accepting Puerto Rico statehood. Indeed a problem with PR statehood is that not all Puerto Ricans want it, some prefer independence, but in a CW context it might seem expedient to settle the matter and quash that once and for all by regularizing PR as a state; its Spanish speaking Catholic population not so strange offset by Orthodox Russians in Alaska, as well as, to round it out, accepting Hawaii at the same time. Perhaps in this scenario Hawaii has annexed to it all US held Pacific Islands--not the UN Trust Territories deeded to us by conquest from Japan, but then again in this ATL those are still Japanese, but Guam, Samoa and other islands here and there, all federated into Hawaii which might have a unique federal state constitution giving the non-Hawaiian parts autonomy. This might bump Greater Hawaii, or we might say the State of Pacifica which HI is the largest part of, into a three-Representative bracket every now and then. That just leaves the Virgin Islands and District of Columbia as territorial anomalies in an otherwise all-statehood USA. Perhaps we might make a clean sweep by biting the bullet of one really tiny state (VI, and this might encourage splitting Pacifica back up into Guam plus any other vaguely regional islands, Samoa and any other small Polynesian islands, and Hawaii itself) and finally reinterpreting the Constitutional grant of Federal District territory to Congressional control to mean strictly actual Federal buildings and parks, plus maybe some tracts of residence reserved for members of Congress and some Federal workers who opt for it, and either reverting the bulk of DC land back to Maryland or establishing it as a city-State with special obligations to cooperate with Congress in their control of the Federal buildings. Then absolutely everyone under the US flag would have equal rights to Congressional and Presidential electoral representation. I am of course assuming that the Philippines are let go, and that special provision for residents of the Panama Canal zone to vote as expatriates from whatever state they came from would be provided as well.
I meant to consider even earlier PODs, perhaps involving the Empire of Japan and of China, or the early RoC, coming to cordial terms of mutual support and development late in the 19th or early in the 20th century, but honestly that seems highly improbable. Or better performance by Japan in the Russo-Japanese war--they decimated the Black Fleet on the high seas but it was something of a stalemate on land OTL--gives them a foothold in OTL Russian territory even before the Great War--the Russians couldn't re-dispute it with Britain allied to both Japan and Russia during the Great War and the Russian Civil War period would keep these Japanese territories out of either side's hands, though per OTL the Imperial Japanese would surely aid the Whites and could not be induced to withdraw from their pre-war winnings, which they might expand with White help during the RCW.
In all of this I have strived to comply with the rather stringent condition of Manchuria and the rest of China (beyond pre-Great War and Great War won concessions, such as Shandong, anyway) be left alone, which I figured could only happen either if the Japanese controlled other resource areas, or enjoyed strong trade relations with another Great power such as the Commonwealth-Empire. Obviously post-WWII, which is a given if Hitler is not butterflied out of power (and IMHO, not going to happen if he is kept from power; other German strongmen might desire some conquests but I doubt they could orchestrate the conditions enabling Hitler to make them OTL; Stalin IMHO is the Great Procrastinator many assume would start European WWII if Hitler doesn't, but I believe he would sit there contained playing Hamlet, never giving up on building a big strong Red Army that could start WWII, but never actually sending that army into battle for deep reasons I won't elaborate here) I am letting the dominoes start falling freely, but again assume as given that the Soviet-Western confrontation without open large scale war (except civil war possibilities in China and the sudden seizure of Far East territory from Japan) as OTL Cold War to exist in modified but basically identical form.
Bottom line re Korea--Korean nationalism puts them into play, provided some great power desires to alienate them from Japan, otherwise they stay Japanese ruled, at least until the Soviet breakup, which I am not certain must happen. Removing the Soviet bugbear might position Korea for gaining independence from a quite liberalized Japan by the 1990s.
