Never been to Japan, but I'm in love with the free party/clubbing scene I've read and heard about down there. :] Seems pretty spiffy. If I go down there, I'm def. living up the nightlife.
Also I wanna' try some of the beer down there, and a certain brand of cigarette that's PEACH flavored. :O
Otherwise, the fashion. I love watching the runway shows from there, and reading their fashion magazines. I tend to like them more then America's fashion magazines (Minus Vogue, I love Vogue) because of Ranzuki, Popteen, and Ageha. The fashion movements fit more with my taste. A lot more girly, eccentric, and out there.
A lot of fashion I see in American magazines pretty much looks the same, isn't girlie enough, or too conservative. :[
Oh, and the art. Several favorite artists of mine are from Japan. :] Of course, I love the art scene in any country, even here.
And FESTIVALS! :O I'd love to go to the festivals down there, it seems so fun!