Interesting news story on MobileIndustry.biz around Namco US bringing KDDI games to the US (Link)
KDDI supports games based on J2ME and BREW, in 2004 KDDI launched the aU service which offered flat rate data at broadband speeds. This revolutionised the Japanese market and proved to be highly popular, helping the network to rapidly grow in a short time frame.
KDDI is Japan's second largest MNO and the largest single territory 3G operator in the world (20M+ 3G users) with flat rate data running at 2.4 Mbit/s.
It will be interesting to see how the titles translate to the US market, in terms of content & technically. In the early 00's I was involved with a company bring Korean content to Europe and we experienced issues which made it a valuable experience.