Moving to Japan for work; looking for practical feedback/input

Preface so this doesn't become a debate thread: I'm aware of the current economic climate, the weakening yen situation, shifting sentiment around foreign residents, and the broader geopolitical picture. I follow this stuff habitually, so I'll lead my post by saying I'm approaching this move as a deliberate 3-year skills-building opportunity. We can talk about these things in the comments but it's not the focus of my post!

Here's the situation: I already work for a Japanese company, but my role is changing. I have secured a promise of employment contract and will move in late Jan/early Feb 2027. With that said, my employer is handling COE and visa. My spouse is joining on a dependent visa initially and will be looking for work in their field; they're fluent, have lived in Japan before, and are frankly going to be more functional than me for the first year. I'm doing language work now (beginner, already tapped into r/learnJapanese and so forth). We're both mid-30's.

Initially I'll be in the Tsuruoka-Sakata area for several months, maybe 6-10 total, then there is a high likelihood we would look at transitioning to a more Tokyo-adjacent area (thinking Saitama, Ota, or Setagaya), more so my spouse can find a role in their field than anything else, and my company has indicated this would be allowed. My salary will be 8M JPY/annum.

So, I'm hoping to get some feedback on the following items, however you would like to provide that.

1. Tsuruoka/Sakata area as a landing zone; what's your honest take? I know it's rural by Japanese standards. I visited and liked it a lot; reminded me of Fort Collins, CO for the foothills and weather. Assuming I can make headway on language acquisition before the move, is this area putting me at a significant disadvantage or is daily life manageable? If you have any region-specific things worth knowing about housing, transport, winter, general quality of life for a foreign couple in mid-30s, it would be appreciated. We do already have local friends (not just through my employer, but my spouse's JET friends) who will help with adjustment.

2. What should I be doing NOW, while still stateside, that people typically wish they'd done sooner? Anything beyond "learn Japanese" and "open a Wise account." I've got the basics covered. I'm more interested in the less obvious stuff. What types of things came up that you had to handle later on that wish you'd handled early?

3. Other specific questions. The hardest considerations in me making this move are largely long-term financial outlooks; opportunity cost of no longer maxing 401k and Roth IRA for 3 years. Where can I get a crash course on NISA investment or otherwise what my options might be? Is a car strictly necessary in this area? What about my future Tokyo-adjacent moves?

Appreciate any input from people with actual experience, especially anyone who's done the rural-to-Tokyo transition or moved as a couple. Double points if you or your own partner work in a Higher Education capacity and have some tips on how my spouse can pursue employment upon arrival.

by AmbiguousAgitator