So what happend to Japan?
A civil war when the war in China finally turned against the military? If thats the case then I'm assuming the democratic anti-militarist won and there doing a whole "slow withdraw" from Korea or trying to keep Korea as a Dominion like Britain is doing.
As for conflict you have two major flash points.
The Chinese-Soviet Boarder and the Soviet-Polish Boarder
Nah, Second Sino-Japanese war started just like in OTL. The difference being thanks to no European theater that after a while more and more countries put sanctions on Japan, as well as sending weapons to the Chinese (Germany, the USSR and the UK). Which resulted to a slight border alternation in favour of China.
Fast foward during the early 50s. A war ready and very jingoist China started a surprise offensive against Manchuria, starting the third and last Sino-Japanese war.
Just before the Chinese crossed the border to Korea and Japan actually using biochemical weapons, the League of Nations intervened.
The end result being to borders ending up like after the first Sino-Japanese war, with Port Arthur remaining part of Japan.
Japan would have to bear the cost of admitting every refugee the Chinese deemed as "Alien occupies" and "traitors to the nation". So every Japanese, a good amount of loyal Koreans. But not the loyal Chinese subjects like Puyi... They would suffer a different fate.
Other than that, no reparations were made.
During all this, the situation in Korea got worse.
Refugees, being secondary subjects and Korea growing in industrial importance mixed with a growing trend of Japanese youth just not having it anymore with the old elite, forced the Japanese government to accept Korea as an equal to Japan in terms of internal politics.
The Korean Empire is reestablished, with it's own parliament and internal decision making to most degree, but with foreign affairs still being handled by Tokyo. Imagine the situation being like Austria-Hungary after the Ausgleich.
To be honest, I had in mind that the Soviets and China would at least be cordial partners, since in this TL they gave more aid to the Chinese in the last 2 wars.
Europe meanwhile is out thanks to closer integration of economies, resulting in a ECSC like organization, as well as continued Franco-British guarantees for Poland and an de facto alliance of Germany and Poland.
But I had in mind a big war between China and India.
Well, big in the sense of how the environment there can allow a war to escalate.
