Well there is probably no greater culture shock than mid america to Japan, and especially Tokyo. The city is too large to suggest any one place for you, as it will depend on where you are staying and your other activities. My best advise is stay absolutely away from any hotel food, or large established foo foo restos. Your absolute best bet is to ask where the local workers go after work or for breakfast and then put your ego in your back pocket and try anything and everything local. I know most will stick with tours and pre programmed itineraries, but it is the worst way to see a new place. It may seem quite daunting at first, but if its your only chance to visit take full advantage and explore on your own. I recently saw this BBC special that may help you a bit about your visit. Rick Stein made his first trip to Japan in this show and has some good advise, and perhaps some places you may try. http://www.bbc.co.uk/programmes/b00794h0
Hope you have a good time, and oh remember your private space...that space that people give you when in a crowd is about 1 centimeter in Tokyo, so don't panic!