The inability of japan to resist that was almost like the straw that breaks the camel's back for this shoganite. They were already kind of rickety, certainly finding it tough to evolve. So we will return things to the way that they're supposed to be, in harmony with the universe,. Back to the golden age where the emperor runs things again.
The Asia-Pacific War of 1937-1945 has deep roots. It also involves a Japanese society that's been called one of the most distinctive on Earth. If there were a Japanese version of Captain America, this would be his origin story.