thesuker, what is your nationality? This may play a role, too. I believe that for native English speakers, you only need 3 years of related work experience. If you are NOT a native speaker, you will need 12 years of your education to have been all in English.
It may also depend on which work visa you apply for: instructor (for ALT or HS work), specialist in humanities (eikaiwa), professor (university).
Read more at this link and its bottom link.
Immigration Services Agency of Japan
I would also like to add this question. How long are you planning on staying in Japan? If it's long-term, then my advice is to get the degree first. Competition among degreed people is fierce here at
all levels of teaching. Moreover, I'm not sure if you are aware of this, but the process goes like this:
- get a job first
- get the work visa later
The exceptions to the second step do not currently apply to you (and may never): having a spouse visa already, a dependent visa already, having a student visa already, having a working holiday visa already. So, if you were thinking that you could just apply for a work visa and
then go job hunting, that's incorrect. Work visas need sponsors, which explains why the process is in the order I stated above.