Changing visa status just before starting job

Hello all,
I want to change my working visa status from professor status to researcher status.
As I am currently away, I can apply for it at immigration office only two days before the starting of the new job (1 nov.) that needs researcher status visa. I am wondering when I will reccive my new card with researcher visa status from the immigration office, the starting date for validation of this status is as same as the date of starting the new job (as i applied for it before starting that)or it is as same Date as I will get my new card (usually it takes to weeks for getting the new card).Thanks!

I am not aware of what differences there are between professor and researcher status in terms of qualifications and what is allowed under each status, but please expect a change of resident status to take just as long as the immigration authorities need, which might or might not be just a few weeks. You might state your job starting date as Nov. 1, but you might not get it until a few (or more) weeks later. The date your new status starts is when the immigration authorities make the decision to grant you the new status.

I think an agent or a new employer can do it, instead of you. thus, you have more time.
generally speaking, a new employer must confirm that a new employee has a suitable residential status for working, before hiring him/her.

You answered you own question the new job (1 nov.) that needs researcher status visa. If you do not have the correct status, you cannot do the new job legally. You are not going to get a new status within two days.
If I was the employer I would be pretty annoyed that you would not be able to start on an agreed date because you didn't have your documentation/status correct. Obviously you made some representations to them about your ability to do the work with the correct status, and it seems you have not prepared sufficiently. You still have around four weeks - you should get your application now.

In the research-based positions where the employment is usually based on the open calls, after the applicants proved that they have enough scientific qualification, the universities fill the immigration forms and ask the applicants to change the staus (if it is needed). I don't know the case, but sometimes the deadline is too short as the academic job was offered in the last minute or the applicant is away for a while for attending the conferences or fieldworks etc.. So, I think such delays are understandable for the academia. This was also happened to me. Maybe you can ask them to postpone their offer for a while as it is usual for the research-based jobs. Anyway, I wish you the best with your new job.

Applying for permission to engage in out-of-status activities while the change of status application is being processed could also be an option.

http://www.immi-moj.go.jp/english/tetuduki/kanri/shyorui/09.html