You don’t think that the relevant figures appointed in a Taft Administration would act any differently?
The keys here are multi-tiered:
1) They need to have obtainable and realistic goals in China to achieve. There is no way they can conquer the entire landmass. They can, however, likely enforce an unequal treaty giving them ports, perhaps some land concessions like the Shandong peninsula and Hainan, and a renunciation of Chinese claims on Manchuria, Port Arthur, and Formosa. The best time to do this would have been using a unified Navy-Army command structure that cooperates during 1938 and early 1939 and offers a peace deal to Chang Kai-Shek, who was reeling at this point. Avoiding fruitless offensives into the interior of China is the key here. Instead, they should focus on trying to capture the entire coastline rather than launching foolish offensives in the direction of Changsha. It should be communicated early on to the Chinese by the Imperial Government that they would like peace and are willing to negotiate to get it.
2) Don't get the US involved, or at least, wait until there is peace in China first. Sure, go after the Dutch and British, who were weak in East Asia, as well as after French Indochina. But don't go after the US and cause it to mobilize if you are simultaneously fighting a land war in China. Roosevelt would be tempted to go to war, but he would have trouble bringing this about without an attack on the US first.
Hitler's view on racial hierarchy mattered but it was a bit nuanced. Slavs were considered the lowest of the low, but Hitler was perfectly willing to have diplomatic relations with Romania and Bulgaria.Assuming that this is a scenario where all three major Axis powers come out victorious (that is, avoiding war with America)... well, the presumption may be that a Cold War would unfold with those countries on one side and the United States, United Kingdom, and the Commonwealth realms on the other, but can we at all guess what the German-Japanese relationship might look like in the long term? Their alliance was pure realpolitik, and that be enough for it to persist after the war, but there are other factors at play. Being a white supremacist, Hitler did seem to buy into notions of “yellow peril”, so the Nazis might eventually distance themselves from Japan for reasons of racial ideology. On the other side of the equation, the Japanese government will probably be much more desperate than the European fascists to eventually normalize their relationship with America and her allies for purely economic reasons.
The key in China was that Chinese unity had to be sundered in some way. You needed to get the warlords to assert themselves. A CCP/KMT split probably wasn't going to happen during hostilities because both sides knew how disastrous such a split would be, but warlords are motivated by their own interests. Perhaps getting the Muslim and Western warlords to see Japan as respecting their autonomy might do it. That would open up a second front and allow for a civil war to commence, and allow Japan to really work on taking control of the Pacific Coast of Mainland China.Agree with others that for Japan to "win" (not "lose less badly") requires a German victory in Europe. Japan needs France and Netherlands to be Nazi puppet regimes and UK to be more concerned with the superpower next door than it's Far Eastern interests.
Then there is a slight possibility that Japan can force a military end to the conflict in China and secure resources through the colonies of the puppet European powers. If the colonial regimes resist then Japan funds independence movements throughout Asia. Completely different mindset to that which the Japanese had but one that could lead to the "co-prosperity sphere" although it would look more like the post war Warsaw Pact / COMECON than the EU.
Kai-Shek will never agree to any peace that doesn't have Japan out of all of the mainland sans Korea. He escalated the war and repeatedly refused peace treaties. As long as he controls the nationalists you won't have peace.
Japan didn't want to be bogged down otl, they wanted peace pretty much from the get go, even after the Marco polo incident Japanese government tried to calm their army down and undo the whole incident. Kai-Shek quite sensibly saw that a long major war would eventually result in Chinese victory. Perhaps if the Xi'an incident results in his death Japan has a better chance.
1) They need to have obtainable and realistic goals in China to achieve. There is no way they can conquer the entire landmass. They can, however, likely enforce an unequal treaty giving them ports, perhaps some land concessions like the Shandong peninsula and Hainan, and a renunciation of Chinese claims on Manchuria, Port Arthur, and Formosa. The best time to do this would have been using a unified Navy-Army command structure that cooperates during 1938 and early 1939 and offers a peace deal to Chang Kai-Shek, who was reeling at this point. Avoiding fruitless offensives into the interior of China is the key here. Instead, they should focus on trying to capture the entire coastline rather than launching foolish offensives in the direction of Changsha. It should be communicated early on to the Chinese by the Imperial Government that they would like peace and are willing to negotiate to get it.
The issue was that Japan's army was completely out of control and the civilian government, which would have had to make the peace treaty, could not guarantee it. Add to that the divide between the army and the navy, which admittedly also wasn't completely subject to the civilian government, and you have a situation in which Japan's ability to make peace is limited. The best POD for Imperial Japan would have been for the militarists to adopt some sense regarding reasonable goals in China, as well as for the government to take control over the military.One of my teachers in university once suggested that had Japanese initial advanced against China went badly/slower than they did IOTL, Japan would have been probably more willing to cease operations and negotiate with China. Chiang might not go along with that though as noted above, especially as in this scenario China's position might seem stronger, so he might be needed to be replaced with someone else for this to work. This wouldn't really answer to OP's question though, as we would be talking about a relatively limited victory here and this wouldn't even solve the wider issue of Pacifc War.
Lots of people are talking about Japan defeating China as part of the victory, but I think that's totally unreasonable (which is why I didn't include it in my version). Yes, the Japanese could, with enough effort and better decisions, have brought the KMT to their knees, but this would still have been a bad result for them; the benefits they would get would be negligible, and propping up their Chinese puppet or puppets and fighting the Communists would have meant a continued long-term drain on their resources which, while perhaps not as bad as the ongoing war in China was in OTL, was nonetheless something they couldn't afford. Avoiding war with the KMT in the mid 30s is a much better path for them, I think the only path that could lead to anything that would deserve the name victory, however difficult it would have been to convince the IJA of that.
What does Japanese victory look like?
It looks a lot like "Speed 3".
Have you seen "Speed 2: Cruise Control"?Which means what?