Japanese internet uses are incredibly wary of foreign websites, fearing viruses and god-knows-what. The Japanese rival to eBay is Yahoo.jp. But unlike any other worldwide Yahoo site, Yahoo.jp requires a separate account, keeping the hairy overseas barbarians at bay. The Japanese rival to Facebook, Mixi (which has been around a lot longer) requires users to have a Japanese registered mobile phone, again apparently to ward off gaijin.
Also, Japanese usage of the internet for such things as paying bills, updating driving licences, and even e-commerce, is very low. Everything is still done with paper communication and paper money. When I was with J-Com (a broadband provider) any change of my user preferences required me to send them a letter.
However, this has changed somewhat in the last couple of years, as many Japanese have joined Facebook, Google and others. As I said before somewhere on The Reg, I think this all started when Apple bludgeoned their way into the Japanese market, with Google following in their wake. Apple succeeded where others failed because they didn't bend over backwards to make their offering conform totally to what the Japanese operators dictated- they simply said "this is the iPhone, you can sell it but we're not going to make it look like a Japanese phone." A rare case where Apple's bloody mindedness has had a positive effect.