With that POD it's as realistic as the Red Army reaching the Atlantic Ocean and then attempting its own version of Operation You-Know-What-Marine-Mammal, all while the Soviet Union is suffering from White Russian, Trotskyist, and Muslim revolts at the same time.
Have a look at Operation Downfall one day, and then level the playing field so that the Japanese have as much equipment as the invaders per soldier, and it's as good as what the invaders have. Now back them up with US troops. What the Chinese are going to go through is going to make the concept of Downfall look like a playground fight by comparison.Could it be done as part of some larger Cold-War-gone-hot scenario? It might be a bit easier if the USSR and the USA were at each others throats-- having Chinese troops landing in Japan might be a bit easier if they were led by the Soviets, right?
Well... shit. Still, easier than having China invade completely by itself, right? Much in the same way that it's easier for you or I to carry a semi-truck on our backs than it is to carry the Titanic.Have a look at Operation Downfall one day, and then level the playing field so that the Japanese have as much equipment as the invaders per soldier, and it's as good as what the invaders have. Now back them up with US troops. What the Chinese are going to go through is going to make the concept of Downfall look like a playground fight by comparison.