Hey man, how long is your dad going to be in Tokyo? I would LOVE to see the iPhone!!!!
Anyway, the language thing might be a problem: the iPod can change between 20 languages or so, but for the iPhone it isn't simply a matter of changing menus to a different language. It's also text input and text prediction dictionaries, for example text input for Japanese will probably be VERY different from English. For starters, many Japanese don't use computers so the process of entering text in romaji and then converting to kana or kanji is not something they're familiar with or comfortable doing. Apple may decide to model the iPhone's Japanese entry system after traditional phones, with 11 columns (ie, 1=a,i,u,e,o 2=ka,ki,ku,ke,ko) because that's what the locals are accustomed to and it works well. In any case, the Japanese iPhone will need a new input system, and since the current iPhone is English-only (no Spanish or French, at the very least) I'm worried that the ability to switch languages on the fly might be absent from a Japanese model as well.
As for "PC Site browser," it's true that many phones come with that feature now, so it's likely we'll see Safari over here. However, if you happen to catch a peek on the train at one of the locals' keitai, you'll find that 99% of them aren't actually brwosing the 'real' internet - they're usually on Y!keitai, EZWEB, or iMode - portals for watered down, spoon-fed internet. (ie if you want to access CNN through Y!keitai or iMode, you have to pay $3.00 a month for that privilege. Nevermind that CNN is freely available online; to access it on a phone in Japan you either have to use PC Site Browser, which doesn't display it correctly and is slower than 56K on my phone despite the fact that it has HSDPA, or you have to pay $3.00 for the watered-down portal version) ...
I guess my point is that there are a number of obstacles the iPhone will have to overcome to be successful in Japan, and even if they manage to shove it down Japan's throat as-is (which I really hope they do) I suspect English speaking people here will be overlooked simply because we make up such a small percentage of subscribers.