Recommendation for a scrivener or law firm in Tokyo to reaquire Japanese national status

I am hoping to get some recommendations for a scrivener or law firm in Tokyo to help my son reaquire Japanese national status. Our 1.5yr old son was born during pandemic and we weren’t able to get paperwork to our local consulate within the 3 month window.

Having done some research (contacted local consulate, talked with some lawyers, etc.) My understanding is our best option is to move there with him (I have Japanese passport so could get spousal/dependent visa), establish a residential address, and work with a scrivener to complete paper work, interviews, etc.

However, I’m hoping to meet with a scrivener/law firm while we are in Tokyo this time to get a better idea of how the process works, understand the chances of our son reaquiring status, etc.

If you have recommendations for scrivener or law firm (English speaking required) or have done something like this in the past, any info would be great. Thanks!