Tax on profits from US options for non-permanent resident

I am approaching 5 years of residence in Japan, and I'm unsure how to best optimise my investment situation for tax purposes with regards to profits from options in the US market.

My understanding of the key points in my situation are as follows:

1. Foreign sourced income not remitted to Japan is not taxable, aside from capital gains from securities purchased after I became a resident of Japan.
2. Profits from US options through a foreign brokerage (IBKR) are classified as miscellaneous income (i.e. not capital gains).
3. Therefore, if I do not remit these profits to Japan, then they are not taxable in my first 5 years of residence.

Can anyone educate me on whether this interpretation is correct? I want to be sure that I am following the rules correctly. I have already realised a capital gain from selling foreign shares this year, so I know I need to file a tax return no matter what.

Thanks in advance for anyone who can help.

Edit: for clarity, I am not from the US.