Like everyone else, I really hope they go softbank.
I wonder how succesfull the iPhone really will be in Japan. It's hard to say. I had been thinking it would be only so-so popular. The Japanese market is (obviously) so different from the US. Even though the most basic phones have billions of features, most people use most phones for calls and messaging most of the time.
I wonder how good the iPhone will be for a messaging culture. I was surprised how well the text entry works for English, much better than I expected, you can get quite fast. But Japanese text entry on the touch at least is a little laggy as it checks for kanji matches, and I'm not sure how fast you could really get. Then again, I suppose no one could guess how fast people would get at texting with regular phones.
Be very interesting to see.
On the positive side, people seem to looooove the touch here. Everyone who sees the touch interface is totally blown away.