Is postwar Japan better understood in terms of a return to the liberalism of the 1920s, or as a fresh start based on Occupation reforms?
In my opinion, this isn't even close. The liberalism of the 1920s, if you want to call it that, was not very liberal. Postwar Japan was so completely remade by the Occupation as to hardly resemble what came before.
Two major things that make the 1920s very unlike the post-war period:
- The Meiji Constitution was not very democratic. Specifically, it allowed the military to hold so much power that the military had, in essence, veto power over everything that happened in Japan.
- Connected to this, militarism was already quite strong in Japan at this time. Japanese troops were already on the Chinese mainland during this time.
These stand in stark contrast with a clearly democratic constitution that was imposed by the Americans and the demilitarization of Japan mandated by that constitution.
I believe that the Occupation completely remade Japan and that the pre-war and post-war Japans might as well be (politically speaking) different countries.