Yeah, sadly they changed their registration process recently so it needs a japanese cellphone. They send you their registration info there so I'm not sure how you'd do it without one, unless there's a way to get a fake .softbank.ne.jp address or something. Though, mixi is starting to lose popularity to facebook, so maybe getting a profile there isn't too big a deal anyways? :-)

From my experience, the Japanese internet is more about anonymity and communication is focused on forums and blogs. People don't usually upload their real photos on mixi and they add people they haven't met in real life, unlike Facebook, which is usually for interacting with real friends. If that's okay, some other sites are: http://pigg.ameba.jp/ --> You can write a blog on ameba, and their side community pigg lets you make a character and interact with people. http://www.2ch.net/ --> For discussing various topics Both are really different from Facebook though, unfortunately...

If registration in mixi is totally impossible for those who don't live in Japan, well then it's fate. But are there any good Japanese social network sites like Facebook or Vkontakte (Russia) or Renrenwang (China)?