According to HKL Nightmare of Battle reports that Dana White told Japanese magazine Kampiro the following:
“A Japan event is already in this years schedule”
According to Kamprio the event will take place in December roughly eleven years after UFC 29 the last UFC event held in Japan. UFC 53 was scheduled for the Yokohama Arena but escalating costs forced a relocation to Atlantic City. The Japanese City and Arena in which the event will reportedly take place are unknown but the Saitama Super Arena, Yokohama Arena, Ariake Coliseum and Ryogoku Kokugikan in Tokyo come to mind.
As for who would fill the card the UFC's stable of former PRIDE stars, former NJPW champion Brock Lesnar and Japanese superstars Yoshihiro Akiyama and Norifumi Yamamoto are all prime candidates my half arsed attempt at being Joe Silva came up with the following hypothetical card:
UFC 141: Shockwave
Yoshihiro Akiyama vs Wanderlei Silva
Antonio Rodrigo Nogueira vs Mirko Cro Cop
Norifumi Yamamoto vs Scott Jorgensen
With the current state of FEG and SRC the time for a UFC event in Japan appears to be now.