There was a new development in Japan in May, 2015, which will soon (within a year) allow any one going to Japan to use their own non-Japanese phone in Japan if the length of the visit is for 90 days or less.
As you have read on this blog elsewhere, the use of any cellphone without a “Giteki Mark” (approval for Japan’s technical standard, like an FCC mark in USA or a CE mark in Europe) is not currently allowed legally in Japan, though I’ve never heard anyone caught and penalized by a policeman for doing it. Japan’s government was aware that this legal policy will inconvenience visitors from around the world for 2020 Tokyo Olympic in the age of instant electronic information. So, Japanese national assembly passed the amendment to the current Radio/Telecommunication Law on May 15, 2015, to allow
– anyone who brings a non-Japanese (with no Giteki mark) cellphone or tablet to use it for less than 90 days after entering to Japan, if the device is approved by a proper overseas regulatory agency.
– and, it looks like a Gaijin-san (who doesn’t have a permanent Japanese address) may be able to purchase a