New bank account options for NISA

Hello. I am currently in the process of receiving a decent sum of money from overseas into my wise account, and am looking to set up a NISA account to get into investing it.

Currently I only have a Japan Post Bank account (was setup when I moved here 9.5 years ago).
I also have a Rakuten Credit Card which just pulls money from my Japan Post bank account each month.

Basically I want to have a bank account purely to hold any money I plan to invest which is separate from my daily-use/salary bank. Like a savings account/bank.

For the month to month it will essentially work as:

Paid salary into Japan Post bank -> Transfer investment amount to new bank linked with NISA -> Invest.

If it is an investment which can be paid by credit card then I will just purchase it directly that way to get the rakuten points, but from my understanding not all investments can be purchased this way.

Is there a recommendation on which bank works best for this type of thing? I was planning to just go with Rakuten since I am already a part of that ecosystem, but wasn't sure if there was a better option.
Simplicity to use when it comes to the banks app would be a big plus.

Will also be transferring directly from WISE to this new bank, unsure if that makes a difference.

Thanks for any insight!

Edit: Am from New Zealand, so any problems with American tax laws and whatnot shouldn't apply for me.

by Drar