Japan has a national mythology that is more intense than most countries. The idea of the emperor as 'divine' was instilled in school children, and it's still there today. It can be used to brain wash people into accepting government policies or even questioning them. If you are a cynical wielder of power, this kind of belief system will work on your population for many years.
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.