Japanese is the national language of Japan.
In education system, everyone learns English so most people know easy English words.
However, you should not expect to have an ordinal conversation in English because they are not so fluent. Therefore, it is valuable to know some basic colocations.
Greetings: Ohayougozaimasu (Good Morning), Konnichiwa (Hello), Konbanwa (Good afternoon), Arigatou (Thank you), Gomennasai (Sorry)
Order something: ~Kudasai (Please give me ~), Kaikei Onegaishimasu (Check please)
Ask Location: ~Wadokodesuka (Where is ~?), Moichido (Pardon me please?)
Hiring a translator is another useful tip when you travel.
Though, it could be very costly.
People need some qualifications to be a translator so that they are all professionals.
It could cost approximately up to 5000 yen per hour.
So, if you do not want to spend money a lot, you should travel by yourself.