Techy folk often talk about how mobile usage in Japan is so high compared to other countries. They point out the souped-up handsets available only in Japan ("high-spec" in Japanese English) with a TV tuner with DVR capability, non-crappy cameras, and other such niceties. But what they forget is that Japanese people use their phones in a totally different way from other countries.
For many Japanese people, the phone is their Primary Computing Device. Let's digest this for a second: They use their phone (or keitai) for computing more than they use their PC (which has "computer" in it's name). We're not just talking about mail or IM (which by the way, no one uses on their phones). We're talking about web surfing and actually doing work. For example, I've been told that college students will look up information and WRITE PAPERS on their phone using predictive text entry. If you told an American college student to write a paper on their phone, they would laugh and go back to drinking.
And the web they are surfing? It's not the same internet you're surfing right now. It's a complete, self-sufficient universe of Japanese-only mobile sites. There's everything: blogs, social networking, porn, shopping, you name it. It uses it's own variation of XHTML and takes into account factors like screen size, input method, and Japan's affinity for all things cute. Take a gander at some of the sites in this gallery.
To me, it looks like someone shoved Geocities onto a Zune, tag and all. But to many Japanese people -- particularly young women -- this is The Internet. The internet you're using now? That's the "PC internet" -- a foreign land where you have you use a full keyboard instead of your keypad. So if you want to tell Japan about your cool website/toaster/robot, you can't just promote it on your internet, you need to promote it on Their Internet as well.
(Screenshot from Asiajin)