How do i get my drivers license in japan?

Question:

I read that you can get your foreign license converted to a Japanese license but the only foreign license I have is an international license issued in japan. I currently have a SOFA license but I'm about to loose my SOFA sponsorship when i quit my job and marry a Japanese national.

Answer:

You do not need to get any other license if you have an international license. You can drive in Japan.

BTW, you need a license of your country before getting an international license. So I wonder how you got international license if you do not have any other.