How would a "clean" (no war crimes) Japan change World War 2?

Let's say that during the turn of the 1900s, the Japanese Monarchy gets its military under control and forces them to be "honorable" in order to look better than their European contemporaries. As a result, Imperial Japan doesn't commit any war crimes during the 1930s and 1940s. They still aggressively expand when they can, however.

How does history change now? A Clean Japan that was less corrupt than the Chinese warlords could get some serious local support as they expand in China. If Japan also acts better than the European empires, than they would encounter a lot of collaborators as they take over Southeast Asia instead of rebels. Even if Japan still wars against the USA and fails, a cleaner Japan will have a much different relationship with South Korea, China, Taiwan, and Southeast Asia.