In a recent report, BlackBerry no longer has interest in selling their smartphone devices in Japan, therefore they will not see a BlackBerry 10 launch there. In a statement from BlackBerry they do however confirm that they will continue to support their customers in Japan. See BlackBerry’s statement:
We are in the process of launching BlackBerry 10 globally in key markets and we are seeing positive demand for the BlackBerry Z10 in countries where it has already launched. Japan is not a major market for BlackBerry and we have no plans to launch BlackBerry 10 devices there at this time. However, we will continue to support BlackBerry customers in Japan. – Via Engadget