Japanese is the language spoken in Japan, but English is widely spoken throughout the country with announcements on public transportation frequently made in Japanese and English, most signs include roman characters or an English explanation. Most Japanese people study English in junior high and high school so you are best seeking out younger people who may be able to help and translate for you.
It is best to have your destinations written down in Japanese so you are able to show this to your taxi driver or people on the street. People are always willing to help whether they can speak English or not.
We recommend you get a good English - Japanese guidebook and familiarize yourself with common phrases such as hello, goodbye, please, thank you, excuse me, and numbers 1 - 10.