I lived there a couple years, if all else fails there is an even higher rate of understanding written English than spoken. In the two years I was there I never felt like I was in a situation ever I needed to know how to read or speak the language(s) even though I did make an effort.
My first experience was having to get from the airport to a hotel in Tokyo to stay the night. A gentleman outside the airport helped show me how the buses worked (those drivers are crazy) and when I got to the hotel counter the gal pulled out a pen and paper since I only knew English and we wrote back and forth to each other. After that my concern over getting lost went away, everyone was really friendly and helpful in my experience.