Japanese colonial empire; Wikimedia Commons.
In the early 20th Century, while mystical idealism, quest for world prestige and economics were important factors, Japan’s imperialism was principally a reaction against the encroachment of Western powers.
In the 1930s, in addition to the “independent” state of Manchukuo, Imperial Japan controlled Taiwan, Korea, Karafuto (Southern Sakhalin), the Kwantung Leased Territory and Nan’yō-chō (former German islands in Micronesia).
A good reference is The Japanese Colonial Empire:1895-1945 by RH Meyers and MR Peattie.
Someone asked if I really agreed with the statement :
“In the early 20th Century, while mystical idealism, quest for world prestige and economics were important factors, Japan’s imperialism was principally a reaction against the encroachment of Western powers.”
If you look at the map on my previous post, you can see that Japan’s concern about security was not far-fetched. Avoiding conflict with Britain & USA, they took on Russia and China and created a buffer zone with Korea, Taiwan and Manchuria.
That said, let me reiterate that the rise of militarism in the mid-1920s (and the increasingly severe repression of moderate dissent) launched Japan on an aggressive path of imperialism.