Best Strategy for Roth TSP/IRA Withdrawal in Japan?

Hello everyone,

I tried to find the best strategy for this question, but I’m having a hard time finding any.

Currently, I am in my last year of university in Japan, and I have a US Gov't contractor job lined up within Japan after graduation. I am in my early 30s with ~$350k total combined in my Roth TSP/IRA. After about 10–15 years working under SOFA, I plan to transition to a PR visa and retire at around age ~45 (I'll have enough saved). However, I learned last year that Japan doesn't recognize tax-free Roth accounts and am worried that I made a very costly mistake.

Assuming the tax laws stay the same as they are today, I was wondering what the best strategy is to avoid double taxation on my Roth. I've been toying with ideas like cleanly breaking tax residency while keeping PR or smoothly transitioning into SOFA status again and withdrawing afterward. The easiest way I can think of is continuously working under SOFA until age 55–56 and withdrawing at 59.5 before becoming a JP tax resident (not ideal).

I am going to consult a tax lawyer soon after I start working for some professional advice, but I was wondering if there are any other ways to avoid Roth tax in a safe and legal way that I haven't mentioned or found in my research. I'm planning early to avoid the mistake I made at 18 years old and to see if it's hopeless, so I can switch to a Traditional TSP next year.

Thanks in advance!