I've eaten quite a lot of food in Japan and some of the more interesting ones i've had on my plate are:
Live squid sashimi; This you eat straight out of the tank. The squid is alive, then slice alive, then served raw. When you eat the legs they attempt to stick themselves (with the little suckers) to the inside of your mouth. The chefs called this "kiss!!!". Oh yeah they also try and wriggle off your plate and hate when you pour soy sauce on them.
Whale dishes; I've had whale in many different dishes - in a mid sized town called Kochi on the south coast of Shikoku there is a decent sized whale eating community. I had whale sashimi, whale hotpot and whale karage style (deep fried in batter). Whale is a red meat and tastes awesome.
I've also seen horse sashimi but wasn't up for it due to the dodgyness of the restaurant i was in but it seems quite popular.
More normal foods I loved over there were;
- Cold soba noodles (great in the summer)
- Tuna neck (giant tuna the size of small boats are cut up - the neck meat is like a cross between beef and tuna and swordfish)
- Chicken curry rice (for 500 yen you cant go wrong)
- Sea pinapple (some kind of see urchin thing you eat live or steamed)
- Chawanmushi (egg custard with suprises of seafood at the bottom)
I was also a huge fan of eki-bento (take away pre-packaged lunch boxes they sell in train stations) which help on those long shinkansen trips cross country.
The best advice I can give anyone eating in Japan though is to find resteraunts with a bar where you can watch and talk to the chefs (and even drink with them while there on the job in some places) who make your food and you will have the best times.
As for drinks i never got into the million varieties of teas but i did like the Boss coffee, the one that comes in the rainbow can is the best. My girlfriend loves the Soba cha but i cant stand the thought of drinking noodle juice.