The next generation iPhone 5 is likely to debut to NTT Docomo users in the next summer 2012, Nikkei Business, which scooped about KDDI to carry iPhone 4S, did it again earlier today on December 1, 2011.
NTT Docomo has the number one market share of mobile phones in Japan. According to Nikkei Business, they have been losing the market share especially after iPhone 4S came out from AU by KDDI and Softbank.
The various rumors from Japanese mobile experts said NTT Docomo has been trying to secure the rights to sell iPhone in Japan last a couple years.
According to Nikkei Business, NTT Docomo executives were finally able to hold the meeting with Tim Cook, the CEO of Apple, Inc., in the mid November, and reached the agreement to carry iPhone 5 under the circumstances.
The next iPhone 5 is likely to support NTT Docomo's Xi (pronounced as crossy), the next generation broadband mobile Internet connection service (It is also called as LTE, Long Term Evolution).
NTT Docomo's LTE system has 5 times as fast connection speed (approx 100Mbps). Other major cell phone players in Japan, KDDI and Softbank, have the late start to support LTE system. NTT Docomo already have the infrastructure available. Apple requested that iPhone 5 can support it. They seems to have reached the agreement.
Now Japanese cell phone carriers, Softbank and KDDI, will loses the advantage of "we carry iPhone". It would be the competition of the network availability.
UPDATE (May 2012): According to Nikkei, soon after the news about the news came out, Japanese mobile phone manufactures became furious. NTT Docomo had to stop negotiating with Apple. There is no more possibility of iPhone from NTT Docomo for a while.