Japan was already an aggressive state by the time of World War I. There was the Russo-Japanese war in 1904. Then they annexed Korea in 1905 and ruled it pretty brutally. The Japanese then engaged in skirmishes with the Russians/Soviets for control of Manchuria, finally getting control in 1931. Japan as a country was in the control of a totalitarian government that advocated turning Asia into part of the Japanese empire. Their logic was that the West had made much of Asia into their own colonies and treated Asians brutally. Which was true. So the Japanese were freeing Asia from Western control--which was also true. Unfortunately, their own control was not necessarily any better. While many Japanese citizens protested against these activities, there was no really effective resistance so there was no real chance that the Japanese empire wouldn't continue to pursue that course. They called the areas of Asia that they controlled "The Greater East-Asian Co-Prosperity Sphere", and tried to join all of Asia under their umbrella of control. They brutally repressed any left-wing resistance within Japan to Japanese imperial activities, killing numerous activists and politicians. Many historians refer to the Pacific War rather than World War II when referring to the fighting in Asia, because the implication of calling it World War II downplays the fighting that went on before the US became involved. The beginning of the Pacific War dates to 1931, by many people's estimations. Others date it from 1937, but yet others from 1941. The point is that none of the growth of the Japanese empire was peaceful, and democracy within Japan was suppressed by totalitarian forces from earlier than World War I, and continuing until 1945.