Jobs for Vietnamese in Japan?

I'm Vietnamese, I'm majored in English, and I plan to study Japanese, too. I feel like languages are the only thing I'm into. I wish to live in Japan someday, but I don't know what I can do with only languages. Is it possible for me to be language teacher in Japan? I also have doubts that my degrees would be accepted in Japan (they're acquired in Vietnam, after all, which makes them not that worthy). Do I have to study a practical major and get a degree in Japan in order to get a job?

It seems many Japanese firms are currently expanding in southeast Asia, so the fact that you speak Vietnamese and English could be useful for an international relations kind of job, but you would also need perfect Japanese, so the most plausible course of action is to study at a language school in Japan to attain N2/N1 level, and then apply for jobs.

This seems like good advice. I'm not sure if it interests you - but some higher end hotels/ryokans employ some people from SE asia who speak English and very good Japanese. I saw exactly this at my hotel in Kusatsu I stayed at last week

Not really language teaching, because the only language you are likely to be eligible to teach would be your mother tongue, Vietnamese, so demand will be limited.

I agree that you might have a chance (once you've reached a certain level of fluency with Japanese) with Japanese companies that have networks in Southeast Asia. If you look around at Japanese companies that have offices/production sites in Vietnamese, you might hit some idea.