After experiencing the difficulties of my uncle's inheritance process, I decided to reduce my own accounts as well.

I narrowed down my accounts to two: Rakuten Bank, which has a high interest rate, and a local financial institution for my business.
I have no problem with two bank accounts. I was not sure whether I should lose the post office bank account or not until the very end. It was very convenient because it could be handled anywhere in Japan, but now, with the spread of online banking, even Rakuten Bank can be used anywhere in Japan.

Incidentally, deposits of 10 million yen or more are not guaranteed in Japan, but you can eliminate the guarantee limit by not receiving interest.
Since the current interest rate is very low, I consider it better to use this system for those who have a lot of deposits.
I invest, so I have only "2 years worth of living expenses" of cash in reserve.