Anime is pretty much everywhere, there's a theme park centred around a particular artist (can't remember who).
Lots of technology, you'll get jealous that their mobile phones won't work here.
Places I recommend-
- kiyomizu-dera. Huge temple built on a hillside, very impressive.
Basically there's a walk through Kyoto where you see lots of the temples. Be prepared to walk up many many stairs.
- Shibuya crossing. Biggest crossing in the world, it's crazy.
- Any toy store in Akihabara. The area is great for electronics, but most of it won't work over here. You can pimp out your ipod with the accessories, though.
- Asakusa. It's a part of Tokyo that's a bit more traditional, very good for souvenir shopping.
- Harajuku, if you're into teenage japanese fashion. It's fun for a browse.
Basically, the most valuable thing is someone who speaks Japanese and a Lonely Planet, and a JR train pass if you plan on going on many trains. Don't be afraid of cheap accommodation.
