@-wahn-:
I myself happen to be what Demon Rin referred to as a "Japanese fan". As in, I read from the particular source whereas others read from scanlators material. Haki is a common word in Japan. Still, that doesn't mean every Japanese person knows what it means or uses it in regular conversation. It's more like there is nothing unusual about the word, and it is used just like the way an English speaker would read the word "ambition". We look at it as an ordinary word, but somehow we understand the word actually has a deeper meaning to it.
This seems like the most important part. I would love to have this explained a bit more.