UWB (ultra wideband) devices will be allowed in Japan this summer (July or August). However, the radio frequency bands allocated for UWB will be quite limited, at least in the beginning. The government recently released a report that describes relevant issues (manly about radio frequency uses. )
One thing that might be worth mentioning is about the use of the 4.2Ghz-4.8Ghz band. Until the end of 2008, it is permitted to sell UWB devices operating in this band even if they don’t use the DAA (detect and avoid) technology. This or nearby frequency bands may be allotted for 4G mobile communication services around 2010.
The rules could potentially change in the near future to make it easier to use UWB in Japan.
via Nikkei
RFID in Japan 