Hey, what's with the Thailand stereotyping? I have a sister in law who sold her house in Boston, moved to Chiang Mai, and pays about $100/mo rent for a beautiful house in a nice part of town. She's got a Home Depot and a Dairy Queen within a mile of her house, her doctor went to Harvard Med, and there's even a decent Mexican restaurant in town.
I'm tellin' ya, as far as I'm concerned, Thailand is the promised land. If only I could convince my wife.
On to Japan: Vader, I assume you're going to Tokyo? If so, bag a direct flight to Narita and, once there, just hop on the Tokyo train at the airport and it'll take you right into town.
Do yourself a favor before you leave: Google (or go to the Japanese consulate in LA if you can't find one) an English-language map of the Tokyo subway system and JR rail lines. It's color-coded, and pretty easy to read, and it'll get you started.
Buy Fodor's Guide to Japan.
If you're a baseball fan, catch a game at the Tokyo Dome. It's amazing.
Memorize the following: "Sumimasen, eigo go wakari maska?" It means, "Excuse me, do you speak English?" People in their early twenties are mostly likely to say "yes" and help you out. Oh, and bow and smile (but not too much, or people will think you're weird) while you say it.
If you go to Yokohama, you've got to ride the giant ferris wheel Godzilla knocks over in one of the recent movies.
I love Japan, and I've been fortunate enough to spend a fair amount of time there. Unfortunately, almost all of it has been in the Tokyo-Yokohama megalopolitan area. If you're going to the other islands, I'm not much use to you. But if you have more questions about T-Y, I'll be happy to do my best to answer them.