Being snarky here. For most Japanese, WWII began on August 6, 1945 with the A-bombing of Hiroshima and ended a month later on the deck of the USS Missouri. The Emperor was replaced by MacArthur as Japan’s ruler.
All that the 1930’s and 1940’s consisted of was a benevolent Japan guiding its Asian brothers and sisters into the Greater East Asia Co-Prosperity Sphere while throwing off the yoke of Western imperialism.
Simple.
They were all on vacation.