Advice: Leaving Japan but still got plans, WWYD?

Looking for specific advice regarding how to navigate my last few weeks in Japan with residence status, insurance, and pension repayment stuff.

I'm leaving the country after my current instructor contract at the end of March. Afterwards though, I'd like to take the opportunity to use my free time to say goodbyes and do some travelling before I go, namely a low-intensity hiking trip and an event where other friends will be.

In all, I'm hoping to stay about another 6-8 weeks, so here's where I'd like some perspective from anyone who's been in this spot before (especially if you've left Japan and returned later!):

  • Residence/Visa: I'm on an instructor visa, and like I said my company contract ends the last day of March. But my current residence is actually approved for 3 years, expiring in 2028. Obviously once I leave my company the 90 day clock starts until immigration checks in if I don't inform them that my contract ended, but either way I'll be leaving before then. My question is, am I allowed to just tell immigration I'm leaving but want to hang out first and switch to a "short stay"/tourist visa? Would it be advantageous to do that, or just keep my current status? As for why it may or may not make sense to change before leaving…;
  • Insurance: My job included 社会保険, which I know I can apply to continue temporarily through 任意継続健康保険. I'm wondering if I should keep it rather than switching back to National Insurance, possibly less paperwork? Also, since I'm hoping to do some hiking where there's a non-zero chance of run-ins with snakes or wild boars, would it be wise to have my current insurance rather than possibly being hospitalized as a tourist? Also, once my contract ends, will I have outstanding insurance payments following me for the month and half I'll exist here without a work contract if I don't change to a tourist visa? And speaking of payments that stop once I leave my job…;
  • Pension Lump-sum Repayment: What makes this all tricky is having or not having an address. I'm moving out of my current apartment (company-managed contract) about a week after my contract ends, then I'm planning to stay with friends and different overnight stays while hiking and other trips. If I want to apply to continue the independent payment for my insurance, for example, pretty sure I'll need a Japanese address. Didn't mention yet but I'll also be selling my car, which I think I'll also need to still have my address for (unless there's any way to sell a car without an address? Car-camping across Japan? Is that allowed?). But to apply for my pension repayment, I need to prove I DON'T have an address in Japan anymore. And I know the process can be done by mail from my home country, but I've seen too many posts around here about people sending their stuff in the mail and not hearing anything from the pension office for like a year. I'm not taking any risks with the thousands I got in there and will do whatever I can to apply in person before I leave, including setting up an account with a colleague to take on the remaining 20% that gets refunded after taxes. So the question here is, would it be worth it to just be a tourist and start the pension repayment ASAP? Or would that even be possible if a tourism status isn't granted?

Lots of specifics here, but I'm really not sure which parts of all this to prioritize. This also includes how any of this stuff may affect returning to Japan if that happens (stuff like insurance lapses or undeclared residence status changes before leaving, etc).

So, anyone who's been in this spot and returned to Japan or know someone who has, what do you think would be a good way to exit? "Don't bother with immigration and keep the benefits just in case?" "Insurance wouldn't make that much difference so drop that address and get that pension money?"

If you were me, what do?

Thanks!

by tsumari-Jicama