RetireJapan

There are two sections in that first reply, "for japan," and "for the US". There's no special system, just reporting to the two tax agencies, and sometimes giving details to one or the other about taxes I've paid outside their jurisdiction.

In my experience, tax reporting in japan is relatively easy, you can even now do it on a cell phone. (even with the 'complication' of having foreign passive income and possible gains). Preparing a tax return on the US side requires more knowledge and work (simplified by tax software).

In the interest of keep-it-simple (KISS), all of my investing is done in the US, none in japan. This is not a "system", just personal choices made. I never a worry about whether something is a PFIC or not, tax reporting on both sides I can handle on my own (no accountant/CPA fees), 24/7/365 online access and the same for phone queries (in english), trades that are now commission free, and some other account services that I haven't seen here. And outside of the FBAR (which takes about 15 minutes), there's nothing in japan to add to my US reporting.

So yes, I'm offering that as an example of what you might do. You are of course welcome to try anything that you prefer.

Yes, thanks for the reply and clarification on the details. Makes sense. I'll have a think and decide if I want to invest in the Japanese market or not. Or just keep with buying stocks and ETFs through US brokerages. I'll still set up my NISA with Rakuten or SBI (depending on which one goes through my paperwork faster) and then take it from there. With things going weird after Fidelity locked me out from putting more into my mutual fund and American Funds telling me not to worry (which I don't believe), it's best to keep options open in case some businesses get stricter.

Again, thanks for the reply.