Additionally, in my experience, what we've seen from a militarized Japan was far worse than North Korea--North Korea hasn't invaded anyone recently. As a regional military power, Japan invaded how many countries, how many times? No, I think I'll remain biased against Japanese rearmament, especially with nukes, thanks. They aren't North Korea NOW, but any country with a tradition of oligarchy and big man government, backed against the wall, certainly could be.
When you witness the truly stunning xenophobia inherent in Japanese daily life, you don't think, you KNOW it's a possibility. Some prefer to call it racism, but every time you hear a Japanese tour guide call whatever's a Japanese landmark the 'biggest in the world,' even if any regional visitor knows darn well it isn't (I have heard this about bells, temples, mountains, subways, trains, and department stores. And it ain't puffing. And as gringo noted, hearing them explain Western 'shortcomings' based upon Japanese racial superiority, you know there's a bit of us-against-the-world xenophobic mentality that Japan simply has never left behind. I have heard said too many times "They could NEVER do this in America, too many ____ people," ____ being any group you care to plug any--usually "black" or "lazy." I can't be happy about the idea that we just arm them and hope for the best, knowing that is the case. I would rather the U.S. defend Japan until my kids are grandparents than seriously entertain the idea that we give a power that so viciously mistreated its prisoners and neighbors a second chance to do it again, before it's eradicated that superiority complex. The potential pitfalls are simply too much given the payoff, and I haven't even addressed the negative impact the U.S. rearming Japan would have on other countries' view of us.