Work Visa - Dual Nationality

I accepted a job offer with a Japanese company. I am a dual citizen (US and Mexico). I am currently living in Mexico. However, in college I was in Japan as an exchange student and my student visa was issued on my American passport (I was living in the US at the time).
However, my family and I currently live in Mexico. If I applied for my work visa at the Japanese Embassy in Mexico with my Mexican passport would that be an issue?
I would rather not have to travel back to US.
Thanks!

No issue.

If I applied for my work visa at the Japanese Embassy in Mexico with my Mexican passport would that be an issue?

I am not sure. If you want to be considered the "same person" as when you had the student visa by the Japanese government, then you should probably use your US passport.

I would rather not have to travel back to US.

There is no need for that. You can also apply for your work visa at the Japanese Embassy in Mexico with your US passport.

You can also apply for your work visa at the Japanese Embassy in Mexico with your US passport.

Not so sure. Probably then he would have to show some sort of residence permit in Mexico, which he doesn't have, being a Mexican citizen.