Getting a Working Visa in Japan
Some people looking into staying in Japan, obviously need to obtain a visa which allows them to stay as long as they would like to. For most people this means some form of working visa, unless you're ridiculously rich.
Japan has a bunch a different types of working visa's which with their own set of requirements and period of validity.
Here's the entire list from http://www.mofa.go.jp/j_info/visit/visa/long/index.html
Professor (Examples: university professor, assistant professor, assistant, etc.)
Artist (Examples: composers, songwriters, artists, sculptors, craftspeople, photographers, etc.)
Religious activities (Examples: religious people such as monks, bishops, missionaries, etc.)
Journalist (Examples: newspaper journalists, magazine journalists, editors, news cameramen, announcers, etc.)
Investor/business manager (Examples: company presidents, officers, etc.)
Legal/accounting services (Examples: attorneys, judicial scriveners, public accountants, tax accountants, etc. certified in Japan)
Medical services (Examples: physicians, dentists, pharmacists, nurses, etc. certified in Japan)
Researcher (Examples: researchers, investigators, etc. at research institutes, etc.)
Instructor (Examples: teachers, etc. at elementary schools, intermediate schools and high schools)
Engineer (Examples: scientific engineers, IT engineers, etc.)
Specialist in humanities/International Services (Examples: foreign language teachers, interpreters, copywriters, designers, etc.)
Intra-company transferee (Examples: people transferred to the Japanese branch (head office of the same company, etc.)
Entertainer (Examples: musicians, actors, singers, dancers, sportspeople, models, etc.)
Skilled labor (Examples: chefs specializing in the food of a foreign country, animal trainers, pilots, sports trainers, sommeliers, etc.)
Highly skilled foreign professional visa
The immigration website only provides a very basic overview of what would be required to obtain one of these visa's.
Important but not so obvious detail: you need a visa to get into Japan (as part of this process you apply for a Certificate of Eligibility - which is really a completely transparent part of the visa application process / just another form to fill in). Once you're in Japan on a valid visa you're assigned a Status of Residence - the original visa you came in with is basically converted to a status.
In order to obtain a visa or a change of status of residence the first thing you need is a company that's willing to commit to employing you in Japan. I found such a company and being an IT guy, we found out we needed to fill out the forms for a Change of Status of Residence from Student to Engineer - having originally entered Japan on a Student visa.
With most visa's or change of Status of Residence applications, you'll need to either prove you have a successfully graduated from University or have 10 years relevant working experience. Relevant in my case would mean work experience as an IT guy. This would include education by the way, but only if it was in the IT field.
I never even started uni, so I had to prove 10 years of relevant experience. The way to do this is to provide your resume and (original, signed) letters from each company you worked for, which state the exact period you worked for that company. Be sure that the combined period adds up to 10 years and that your resume and the dates in your letters match up perfectly and you're set!
Submit these and the relevant forms to immigration and you should be able to get you're visa / change of status of residence cleared.
Officially this can take up to 3 months. But if everything is prepared properly and the immigration office isn't so busy, it can be done within 2 weeks up to a month.
Luckily this entire process was supported by my employers lawyer, taking out much of the guess work and making sure everything was able to go smoothly. While the preparation took about a month (getting the letters, correcting my resume, filling out forms) I got my change cleared within 2 weeks. I now have a work permit for any job that falls under immigrations definition of "Engineer", valid for 3 years.