It can be hard to get proper information regarding overall work in Japan. It is possible, but generally it will depend on the job and it's details. I would first try research job sites with offers in Japan and see if you come across anything, if you did it might give you an overall idea what to expect in requirements and what you get out of the job.

Generally, what iv come across about jobs (not all, but some) in Japan is that you require:
- Education (at least a Bachelors Degree, but generally the higher your qualifications the better)
- Work Experience (at least a couple of years experience in your field)
- Langauge Competency (Commanding a very high level of Japanese)
- Japanese Certificates: If you wanted to practice or become Certified to work in certain related areas you have to do the required licensed Japanese certificates to prove you're capable of work. For example becomming a Doctor, Dentist etc

Generally why teaching English is No.1 job for Foreigners (and also possibly the easiest to get work for) is because it doesn't have the same restrictions as the above, you just need a Bachelors degree in any discipline.