Retired (but still active) trader in Japan – What’s the best tax option for me?

I'll try to keep it simple but feel free to ask questions if you need.

I'm a retired American and a day trader, and married to a Japanese national. I am independently wealthy (or at least I have plenty of capital to live off of passively). I make passive income trading, selling monthly put options specifically. My spouse and I are planning to move back to Japan in a few years and I'd like to continue trading full time for passive income. I don't plan on getting any kind of in-country employment in Japan after we move.

Basically, my main concern is making sure that I pay my taxes correctly and that I'm able to send myself a monthly stipend from my Schwab account.

What would be the best type of way to report income and move money? Technically I'd assume that it's foreign earned income as far as US taxes are concerned because this is money in a Schwab account that is on the NYSE. Should I set up a corporation and file a blue tax form, or just compile all my trades throughout the year (usually only 10-12) and submit them as capital gains taxes?

Is anyone else out there doing the same thing as a freelancer/independent investor?