The Premiere 12 is slated to take place next fall. Japan and Taiwan were mentioned as possible venues for the tournament, but according to the latest reports, Japan may no longer be a viable option.
"There were discussions about holding [the tournament] in Japan and Taiwan, but that might difficult to do. Japan alone is very unlikely," said NPB Secretary General Atsushi Ihara.
[UPDATE 5/14 @ 5:41pm]
According to ZakZak, the IBAF may have been hoping to receive financial backing from Japanese sponsors, but with the NPB pushing the Samurai Japan business model, there may be less money available.
Source: ZakZak 5/14/2014