visa extension

I'm from the Philippines and I applied as an English teacher here in Japan and fortunately I got accepted. Now, I do have a little problem my tourist visa is about to expire on the 12th of September and I learned that the processing of my working visa may take a month or two. So I need to request for an extension at the immigration but the problem is I don't know what reason to give them. Is it okay to say that I'm waiting for my working visa? And do I need to present supporting documents from the company? I need a sufficient reason for the grant of 3 months extension here in Japan. Thanks a lot. I really need help.

If you have already applied for your working visa, there should be a stamp in your passport with "Application" on it, which means that it is fine for you to stay in Japan even if your tourist visa expires. Do not let your tourist visa expire if you haven't yet been to Immigration.

It depends on what you have done as the most recent step:

Did you a) apply for a "visa" when you were outside of Japan or b) did you apply for a certificate of eligibility or c) did you apply for a "change of status of residence" while inside of Japan?

In cases a) and b), you will have to extend your tourist visa. The reason "waiting for my visa" should be fine.

In the latter case, you can (and actually are supposed to) stay in Japan while your application is processed.

Confirm with the immigration office as quickly as possible.