Japan sounds like a really neat place to visit, but I think I'd quickly be overwhelmed by the fact I couldn't read any street signs the way you can in Europe. If you want to know where a Cathedral is in Florence, you can just look for a sign that says "Cathedrale" or something similar. If you want to know where some temple is in Japan, seems like you'd have to know how to decipher moonrunes.
Getting around central Tokyo is pretty easy. All the station signs are in English, plus there is more than enough Tourist Focused leaflets available to find those things.
It is handy to learn some Kanji but only if you intend to stay for a while. The length of time needed to become proficient and comfortable reading them, is was too heavy if you intend on visiting for a week or two.
Also finding Temples is super easy if you head to Kyoto. They are all over the place! Pretty much trip over them!