Knowing Japanese will help a lot. No need for an interpreter. Even Japanese people know English is not spoken, but it is patriotism. Signs or other signage is in Japanese.
The Japan language helps. Do not use interpreters English people in Japan, even though it was not popular to say, because it is a nationalism. Signs or other signs, it is the language of Japan.
I know that the Japanese language is not to be used to help you get more Japanese interpreter, even if you know English, but it was not very popular, because it is a sign of nationalism or any other label, it is a Japanese