But, the Chinese government being what it is, you have to consider it when deciding to live or do business here.
Japan was indeed once a dangerous and belligerent actor on the world stage (Nanjing massacre, sex slave camps, attempted genocide, and lots more evil stuff.) However, Japan's military was then thoroughly annihilated, its cities were nuked, its capital was burned to the ground, and most of its leaders were put to death. Throw in a new constitution protecting human rights and the creation of a functioning democratic government, and we end up with an extremely different Japan today, 67 years later.
And (in my opinion), today's Japan is a really great place to live and to do almost any kind of technology-related business.
So I'm not making any statement absolving Japan's historical atrocities (incidentally, I'm American, and both my grandfathers fought against Japan in WWII). But I also don't think they are all that relevant to the times we live in. The perpetrators are now all dead, and the empire they fought for was thoroughly dismantled before I was born.
On the other hand, I'm a lot more interested in what's happening right now. And as far as I can see, Japan doesn't threaten its neighbors or the stability of the region in any way. China, on the other hand, with with its recent threats of military action against Japan, almost daily maritime incursions into Japanese territory, support of North Korea, and so forth, seems extremely unhelpful. (Plus, that whole totalitarianism thing... historically, seems to usually end badly.)
So as a practical matter, I think that the interests of regional stability and peaceful business pursuits would probably be better served if Japan had a military more in line with its economic power, rather than relying on the protection of a country across the ocean, most of whose citizens couldn't find Japan on a map.