[Josh Grisdale]

The best option might be to go to a university affiliated hospital with dentistry. Here are some:

https://www.showa-u.ac.jp/en/medical_care.html

(Just search the page for “dentistry”)

You are more likely to find English speaking staff and accessibility.

HOWEVER, when going to one of these big hospitals, they often want you to have an introduction letter from your normal place. Though, they are also understanding if it isn’t possible but you may need to fill in extra forms saying why you don’t have a letter…

If Japanese is your biggest concern, I know that @takeshi is introducing a service to help people in your situation. Perhaps he can help?