I think that the point is what are your skills. What can you provide to the Japanese society?
- English level
- Japanese level
- Technical skills (IT, design, marketing, etc.)
etc.
I came in Japan 2 years ago without any ideas about what to do and I found a job in just 10 days. But I had a MS computer science and I already spoke Japanese fluently.
Thus, teaching English can be the best opportunity (and a very funny job) for people who don't speak Japanese yet nor have technical skills