The easy (and unauthorized) seizure of Manchuria by local Japanese army units did a lot to weaken civilian control of the military, and started Japan down a dark road. To make this scenario work, you would need to abort that easy takeover of Manchuria.
How do you do that? Mainly by curbing Zhang Zuolin (the Old Marshall)'s ambitions. He was doing very well as the ruler of a de facto independent Manchuria, with a thriving economy and a good military as warlord militaries go, but then he tried to take over northern China and essentially bankrupted himself in the effort. At that point the Japanese assassinated him, leaving his playboy/dope addict son in charge. The Young Marshall eventually turned out to be a pretty good leader as warlords go, but initially the Old Marshall's death, on top of military defeats in China and economic chaos in Manchuria left Manchuria as easy pickings for the Japanese.
The struggle for northern China, and the whole warlord era is extremely complex, with a lot of major factions that most non-Chinese have never heard of. I'm not sure how that struggle would have played out if the Old Marshall had stayed out of it.
In 1924, before Zhang and his Manchurians moved in, the Zhili clique controlled much of Northern China, including Beijing and the Chinese bureaucracy there. They were arguably as close to a national government as China had at the time, with a reasonably powerful army and one of the better Chinese generals at the head of their army. Unfortunately for them, Zhang, with Japanese help, bribed a key general out from under them. The general seized Beijing while most of the Zhili cliques forces were trying to stop Zhang's invasion, and formed his own clique, which ruled large parts of Northern China jointly with Zhang and his Manchurians for a short time before they had a falling out that led to a confused series of wars that eventually caused Zhang and his Manchurians to bankrupt themselves. All of this fighting in the north was extremely destructive, and it delegitimized all of the participants in the eyes of a lot of Chinese. It also made the Nationalists task of taking over Northern China much easier when they made their move a few years later.
To some extent this was a proxy war, with, ironically, Zhang and his Manchurians supported by the Japanese who later assassinated him and the Zhili clique supported to some extent by local British interests.
So if Zhang decides to stay home and build up Manchuria instead of meddling in China proper, his rather formidable army remains intact and deters the local Japanese troops from their unauthorized takeover of Manchuria. That also leaves the Zhili clique intact though, and makes it more difficult for the Nationalists to take Northern China. It's possible that we would see a prolonged period of maneuvering between the Zhili clique and the Nationalists.
The Great Depression, assuming it happens on schedule, would add urgency to Japanese efforts to expand. All of the European empires went protectionists, and Japan needed raw materials and export markets. Manchuria would have still been the logical way to expand, but the Japanese might have tried indirect economic control rather than military expansion, assuming that Manchuria remained stable and with a powerful military.
As happened historically, German would meddle in China, as would the Soviets. I suspect that the Nationalists would be forced to endure Russian meddling for much longer under these circumstanced, because they would need Soviet training and arms to deal with a more formidable set of opponents in Northern China.
Germany would probably not ally with a non-militaristic Japan. They would probably ally with whatever Chinese faction would give them access to vital raw materials, especially tungsten. Historically they allied with the Nationalists for several years in the 1930s, arming and training the Nationalists' elite divisions, in exchange for access to vital raw material. Historically, they broke that alliance when full-scale war broke out between China and Japan in 1937.
Losing Chinese raw materials was a major blow to the German arms build-up, so figure that the Germans become stronger faster in this scenario. On the other hand, as somebody mentioned, the Brits don't have to worry about Japan as much, so they may take a firmer hand in Europe earlier.
