Accessing an old current account long dormant

Hi first-time poster here, so be kind please!

Any tips for getting help accessing an old Japanese current account?

I lived in Japan on the JET Programme pre 2016 and foolishly left an account open with money in it. I still have my bank book and the bank card for the account and all the relevant details.

My Japanese only ever got to N5 and a bit beyond and I haven’t ‘studied since I left & I’ve few bilingual contacts left there that i’d be comfortable bothering to help me with this.

thanks

A