Google's translation app seems to be useful.
They have both for Android and iOS.
Many of the restaurants have the English and Japanese menu. And also most of the Japanese restaurants use the menu with the photos, so you can see the dishes and can see how it look like. Oh, and some of the restaurants use "food sample (the replica that was created by the wax or plastic)" to attract the visitors! That's will really be amazed you! Overall, you don't need to worry the menu!