Are you worried that your existing medical issue might be upset when you are in Japan?
But are you really concerned if you had to go and see doctors there while you travel?

There is a very good service available.
Medical Interpretation Service

orthopaedics-in-africa-1466621-639x411

It is a service you can use the phone you have now.
You don’t need a dedicated equipment.
English, Chinese and Korean interpretation support available.
Pre-booking not required. Just make a phone call when needed.