In major tourist hot spots like Hakone, Nikko, Kyoto and Kanazawa, the vast majority of luxury ryokans will have at least one English-speaking staff on hand. Fufu and Hoshino properties, in particular, have a high percentage of foreign staff that cater to foreign visitors. Ditto for internationally renowned properties like Asaba and Takefue. One good way to find out: see if the ryokan have an English language version of their website; that should be an indication of their intentions.

Many younger Japanese can speak rudimentary English. Relying on Google Translate on your phone should be sufficient for anything but the most complex of interactions.