At this point in time, Japan hasn't been out of its medieval period for even 100 years.

It's nothing short of amazing how quickly they were able to modernize. It's, what, not even 40 years from the start of the Meiji Restoration to whipping down an established Western power (Russia) in a war?

But culture and mores don't really modernize quite as fast. Some things just take a couple generations to shake out. I mean, think about that for a minute -- during World War II you've still got Japanese alive who were alive during the isolationist and essentially medieval Tokugawa shogunate.

People who are a generation or two away from being an incredibly xenophobic society just aren't going to have the same sensible notions of surrender to a foreign power and what kind of battles they can and can't win as other people, including modern Japanese. This is the same culture and time that created kamikaze pilots -- a land war on Japanese soil at that time is going to be bloody as hell.