Getting married in Japan – Spanish + Japanese couple currently living in Spain – Need help with process and timing

Hey everyone,

My Japanese partner and I (Spanish citizen) are planning to move to Japan and get married there, specifically in Kashihara, Nara, where she has her honseki (family registry). We both currently live in Spain, and here we are registered as “pareja de hecho” (civil partnership), which is why she has a visa to live in Spain.

Our goal:

Get legally married in Japan.

Apply for a spouse visa so I can stay in Japan without having to leave after my 90-day tourist visa.

We have a few questions and are hoping someone here who’s been through it can help or confirm:

1. Does my Japanese partner need to re-register her residency in Japan before the marriage?
   Since she already has her honseki in Kashihara, can we just file the marriage there without her moving back in advance? (We would prefer to move together)

2. Documents for me (Spanish citizen):
   From what I’ve read, I’ll need a recent birth certificate and a “certificate of no impediment” (single status) from Spain, both apostilled (Hague) and translated into Japanese. Is that correct? Any other documents?

3. Tourist visa marriage:
   Can we get married while I’m on a 90-day tourist visa?

4. Processing time:
   How long does it take from submitting the marriage paperwork until it’s official? Is it same-day if there are no issues?

5. After marriage – visa status:
   Once we’re married, can I switch from tourist to spouse visa inside Japan? Will I need a Certificate of Eligibility (COE), or can I apply for the change of status directly?

Do we need to register the marriage in the Spanish embassy? I read I need some paper from them to apply for immigration.

Is there any temporary permit that lets me stay in Japan while my spouse visa application is being processed?

If anyone has gone through this recently (especially in Nara or Kashihara), I’d really appreciate your input. Official government info is helpful, but personal experience would be amazing.

Thanks!

PS:
I think this is the most straightforward process, but if you think otherwise let me know (getting married in Spain and register the marriage in Japan through embassy, get the COE from Japan etc)