In Japan, is the opposite of white is red?

I have a very annoying professor who is of Japanese descent but is Brazilian, just like me. He has an ego, and one of the things he said is that in Japan the opposite of white is red, not black. If this is not true, it's quite annoying because he teaches design. I tried researching it, and it seems like it's taken out of context, and the opposite of white is black, but I didn't find anything concrete. So, can you clarify this for me?

My theory is that the opposite of white has always been black, but the opposite color of white is red, just like the opposite of red is blue, like in team fortress 2.

Anyway, I'd like to understand the meaning of these colors; I think it might have something to do with the Japanese flag.

Please help me understand.