Hello,
I am a native speaker of Japanese, living in Japan.
It seems like you need to learn Japanese for work purposes.
While I am not a linguistics expert, I am deeply interested in languages, and until a few months ago, I spent a year studying English in Australia.
One thing I have realized is that generative AI (such as ChatGPT) can be very useful for language learning. It is often better to ask it for the expressions you need rather than using something like a textbook, since everyone's needs are different.
When it comes to practicing with real people, I think I can help. In particular, I have over seven years of experience working for an company in Japan (AKA JTC), so I believe I am well-acquainted with the unique usage of business Japanese.
With that said, I would be able to guide you primarily how to use AI to learn business Japanese.
If you are interested, please let me know.
I will consider how with you.