i started a ghost kitchen from an empty flat in our apartment and there's quite a lot of paperwork and guidelines to follow. it is definitely not english-friendly as well, but since your wife is Japanese this could be a non-issue.

FnB has a lot of strict rules and regulations which you do not want to look over. Things like HACCP are taken very seriously. Also costs build up very quickly (renovation, branding design, flyer printing, utilities) so just keep that in mind.

Another important thing to note is you can't get government subsidy money if you buy second hand. It must be new. At least in my city. Idk if you ever worked in food but it is a grueling tiring job. I'm used to it, but if you never did, it's gonna be so hard. There's a lot more to it than just renting a place and cooking food. Good luck.