uh, what? how about "half", the exact word that 'hafu' is supposed to emulate? you can't borrow a word from another language, and then claim it's unique to yours!
i'm fairly confident nearly everyone on earth knows what it means to be 'half', or just mixed race/ethnicity in general. in fact there are even places on earth where mixed race is the norm. try going to brazil. FUN FACT: the largest japanese population outside of japan is there. i think they might have a concept of hafu there. just maybe.
if you're paying attention, i think the above statement tells us more about japanese culture than the entire article, on many levels.