When one searches for information about a Japanese porn star, one obtains blood-type information.

Why?

It's a cultural Japanese thing. Some of them feel that blood types can tell something about a person.

You could think of the way it works as a little like astrological signs and fortune telling.

Certain blood types are thought to make a relationship more compatible as well.

I have seen condoms with blood types printed on them.

Blood types in Japanese culture - wiki link.

EDIT: Admiral is right, it's just a superstition. And in North American terms it would kind of like knowing a porn girl's favorite topping.

Because the Japanese (and many other East Asians) believe that blood type determines characteristics of personality. It's just as stupid as astrology.

I'm not 100% sure this is the reason but the japanese treat blood types similarly as we treat our astrological birth signs. Its looked at as an indicator of certain personality traits or compatibility as a mate.

http://en.wikipedia.org/wiki/Japanese_blood_type_theory_of_personality

Loop answered this awhile back. He said something about
the Japs being very detailed in their fanaticism, needing to know every detail etc.

I've also heard that blood type to them is like astrological
signs to us. They identify behaviour and personality patterns accordingly.

Edit...Answered.

Bomb them again.....

Or that ^

Such attention to detail. They must make excellent stalkers/

Say what you want about the japanese but they do produce some very entertaining smut, if you can find it uncensored. I know when I can't find a good pron vid or a depraved online story I can still count on some hentai to get the man chowder flowing.