Primarily, at least in my view, the Militarists and industrialist had taken over in the 19th century when they supervised the marginalizing of the Emperor, and the persecution and destruction of the Samurai class.
Then why was Japan a respectable member of the international community before 1932, signing disarmament treaties, treating its colonies at least well (and in the case of Micronesia and Taiwan, far better) than European powers, expanding the suffrage, cutting military spending after WW1, etc?
Japanese expansionism is a sign of some sort of misconception about what being a western style great power is, whereas the partition of the Ottoman Empire and conquest of Africa by the British are in no way inimical to the perception of them as a liberal, civilized great power.
That kind of laid a trip on their heads and gave them a serious amount of "Get our before someone else gets it and get the westerners back. That and the desire to create an asian sphere of protection free from European machinations..
Yea, one of the things people forget is that the Brits and other powers almost created treaty ports in Japan, and had a habit of bombarding the cities when the Japs were uppity.
This is one of the reasons that the war with the western powers was more popular than the China war initially.
On the other hand, I'm thinking that this socialist movement could have been a reaction to the stifling school system.
And not caused by labor unrest, desire for change and liberalism, etc?
Taking the Germany/Japan comparison further it appears that paradoxically losing wars causes Nazis to rise in Germany, while winning wars causes militarists in Japan.
I would argue that winning wars would have emboldened the militarists in Germany, and perhaps led to a permanent "silent dictatorship."
But I also don't blame Hitler for Germany's gleeful desire to conquer Europe repeatedly. This is where I'm gonna plug
The Ideological Origins of Nazi Imperialism again.
I would argue that a POD to change OTL Imperial Japan would have to start around the Meiji Restoration.
It all builds from the Restoration, picks up speed during the First Sino-Japanese War, Russo-Japanese War, World War I, and hits it's high point with the beginning of the Second Sino-Japanese war and WWII.
Wait, why does the Sino-Japanese War and WW1 indicate some sort of disease in Japanese culture? Why was Japan such a model member of the international community before 1930?
People keep repeating this model of Japan that does not square with how it actually acted during this period.