Things I learned on the trip:
I actually am a people person. I never thought I was, but the crowds never bothered me. In fact, even the thought of riding the rush hour trains didn't really bother me by the time I left -- I actually found the crowds rather calming. It's somewhat telling that the creepiest moment in Japan was walking through some part of a station somewhere in the middle of the day -- and there was nobody there. It was damned eerie, actually.
Also, somewhat related -- I don't like travelling alone. Not to say I didn't still have fun, but I prefer sharing the experience with someone -- it makes a huge difference to me. And travelling through the edges of Japan by myself was downright lonely. It would have been (a bit) even without the language barrier, but that just made it more pronounced.
It's astonishingly easy to avoid fish in Japan. I would have thought it was harder, but it really isn't.
I barely ever took off my shoes -- I thought I'd be doing it a lot more.
Japan is astonishingly tourist-friendly -- short of someplace completely inaka (like Oga), you can get around with pretty much no knowledge of Japanese at all. And in Tokyo or the major tourist attractions, it's downright trivial. Of course, it always helps to have some, depending on what you really want to do. And being able to pick out kanji is very useful for figuring out schedules and rail maps and such -- if you can't do that, you're gonna want to have good maps.
Getting around the cities is generally pretty easy. Getting around Tokyo and Yokohama is downright trivial.
I just love the trains there. They're calming. They're comfortable. They go everywhere. The buses still scare me a bit (do I pay now? Do I wait? Where the heck is this bus going again?) but the trains -- the trains are great.
I was surprised at how quickly I got comfortable there. And I stayed that way. I hated to leave. Maybe someday, if I'm looking for work again, I'll look there. Don't think I'd stay more than a couple years, depending on how quickly the inevitable annoyances piled up, but it'd be nice to do that for a while.
And for the record -- I did lose about ten pounds on the trip.