I've been three times, for a total of 6 weeks. You can get by without speaking or reading Japanese, but then you're just another tourist and you'll be sort of relegated to the touristy activities. You can check for guides, usually free or for a small fee, to help you see the sights or just get around. Don't bother getting a car, especially if you're only going to be in Tokyo. Trains and subways will get you pretty much everywhere you'd want to go.

Forget what you learned in anime. Do not use 'yo' at the end of sentences unless you're mad. Pretty much stick a "kudasai" or "onegaishimasu" after everything you say, which means "please" or is just being polite. You'll definitely want to learn "sumimasen" which means "excuse me" to get someone's attention or to excuse yourself for being a dumb tourist or for inconveniencing someone.