Job after language school

Hello.
Not so long ago I started to prepare for going to Japanese Language School from Russia for 1-2 years. My goal was to study hard and then try to find a job as a programmer (Android/Mobile). On the side note, I have an university diploma. There was an interesting requirement for getting VISA. A sponsor (it could be me or my relative) should provide not only a reference to the bank account with money but also some kind of a certificate that he/she worked last 3 years for one company and had $1000 per month. And here where the problem comes. Last 6 years officially (it means I can get a certificate) I was software QA (tester) in 2 different companies (at the first I was also responsible for automation of testing processes) working at the same time as a freelancer programmer for last 3 years (it means I cannot get a certificate. Only my portfolio). And I need to specify in school's questionnaire my jobs. Thus I am afraid that this "history" of 6 years of QA will make me struggle looking for a programmer job in Japan. The language school of my choice helps their student to find a job thus they will use that questionnaire which of coarse will not contain any portfolio.

P.S. Sorry for mistakes and thank you for you help.

Just a few things that come to mind as I read your post:

- Are you talking about a work visa or a student visa?? For a work visa, it will be your future employer who will be your sponsor.

- Please be sure that your "diploma" is at least equivalent to a "bachelor's degree."

- 1 or 2 years of language study will probably bring your Japanese language level to one that would make you eligible to enrol in a university in Japan. I doubt if those will be sufficient to bring it up to a working level.

- What you have (as work experience) is what you have. I am sure that you can add your portfolio information when you reach that point in time when you want to start looking for a job in Japan?

My intent to get student visa going to school, learn hard, find a job changing my visa to working one.
I know people who did so. And they went to school with zero knowledge of Japanese (of coarse I understand that I may turn out not being of the same kind).
I also know a guy from my city who learned language in Russia for 3 years with tutor and I assume it was not so effective as studying language in its environment. The last summer he moved there as a programmer.
Unfortunately I do not have money for Japanese university and I really doubt I am able to win some kind of grant. However my diploma is equal to bachelor (actually it is kind of between bachelor and master degrees. The legacy of past Russian university system)