Hapa is just another term used to describe someone of a mixed race. Like me, who is half Korean and half Black. It is mostly used in Hawaii, where Hapa is an Hawaiian word meaning half or portion of. However, it is becoming more mainstream and being used all over the States.
So, that is why I happily use the word hapa.
I first learned this word when I was living in Hawaii and a local explained it to me after I told them what I was made of :) BTW...Hawaii is filled with Hapa people, which is why I consider it one of my favorite places to live. For the first time in my life, I was surrounded by people who looked like me!