I am not a native English speaker and neither is my therapist. We are both trilingual but in different languages so the only language we do share is English so that’s how we communicate.

I speak English 99% of the time just because how my life played out so I feel that I can express myself and my emotions adequately even though I’ve learned it in my 30s.

Have you considered looking for Japanese speaking therapist if you feel it would work better?