I showed up a bit early at 7:40AM (traffic wasn't as bad as expected) and had to wait outside. At 8:00AM I was allowed to go inside. I received a number and had to organize my documents to easily hand to the officer during my interview.
When I was called up to the window, I asked if there was a Japanese interpreter or if I could do the interview in Japanese. The officer asked me (in Japanese) if I could speak any English. I said I could speak some and she said that we would try to do it in English first (like an English teacher). The interview was easy and so I was able to do it all in English.