Blood!

Blood. No, not the gross kind! Blood types. Whether you love them or hate them, you have one. Personally, I have no idea what my blood type is. I'm 99% sure it's not O, though. But if you ask a Japanese person, they will more than likely be able to tell you. Not just that, but they will be able to read your personality if you tell them your blood type.

In Japan and Korea, it is believed that a person's blood type can reveal many intimate details about their personalities and their compatability with other people, in the same way that Horoscopes in America try to offer vague insight about such things. Ultimately, though, this is just another stereotype perpetuated by scientific racism, similar to phrenology.

In Japan, blood type compatibility is often used in women's magazines, daily horoscopes, matchmaking, and celebrity profiles. Unfortunately, there is a dark side to this, known as bura-hara (blood type harrassment). It can lead to profiling, bullying, and division of social groups. Imagine interviewing for a job and having your potential employer ask you "what is your blood type?"

In all honesty, I have never been intrigued enough by this nominal trend to identify my own blood type. Although Japanese natives tend to balk when I tell them I don't know, it's never made into a big deal with foreigners.