Taxes When Working Partly in US and Partly in Japan

Hi all, does anyone work partly in the US and partly in Japan?

I'm a US citizen and a permanent tax resident of Japan. I have a job at a Japanese company in based in Japan.

If my employer gives the okay and the exchange rate settles down, I'm thinking of working 3 months out of the year from the US. For taxes, I'm guessing I would:

1. Pay 3 months worth of US income taxes to the US

2. Pay 9 months worth of Japanese income taxes to Japan

3. Use tax credits (not FEIE / bona fide resident) on my US tax return to excuse myself from paying taxes on the #2 income,

4. Use tax credits on my Japanese tax return to excuse myself partially from paying taxes on the #1 income. I understand the Japanese taxation rate is higher, though, so I'll likely have to pay the difference.

5. Get paperwork from my company regarding coverage under the social security totalization treaty so that I only have to pay Japanese pension (and not US SS).

6. Continue paying into Japanese health insurance but also get long-term travel insurance in case I get deathly sick in the US.

Before going ahead, I will be sure to talk with a tax professional, but I wanted to see if anyone had any insight.

Thanks!