Type B
People with blood type B are the most practical of the blood groups. They are specialists in what they do. When they start a project, they spend extra time understanding and trying to follow directions than others might. When they are doing something, all of their attention is focused on it. They tend to stick to a goal and follow it through to the end, even if it seems impossible. They tend to be less than cooperative, as they like to follow their own rules and their own ideas. They are individualists. B type people pay attention to their thoughts a little more than their feelings, and therefore can sometimes seem cold and serious.
People with blood type B are often considered more relaxed, freewheeling, and unconventional than other types, although not necessarily to an unacceptable degree. In anime, the genki, off-the-wall types are type B, along with any kind of well-intended character who's ruled by their impulses.
Naruto, Duo Maxwell, Miaka, Nuriko, Tasuki, Sagara Sanosuke"I was very amused to learn that south-asians like Koreans and Japanese make a great deal out of blood types. Apparently B types are bad boys, yeah! Wait, it gets worse.
In south-Asia (India excluded), the subject of linking blood types to personality took off with the 1927 publication of a series of articles by Japanese scholar Takeji Furukawa called "The Study of Temperament Through Blood Type."
The concept hit pop culture and mass media in 1971 when Japanese writer Masahiko Nomi expanded upon Furukawa's ideas and wrote "Understanding Compatibility from Blood Types."
Type-O people were described as outgoing, expressive and passionate. Type-A were considered introverted perfectionists while type-AB were an unpredictable, distant lot.
And then there was type-B. They were considered independent spirits with strong personalities. That exactly matches my personality 
However the cultural stereotypes projected are much worse. There are many characteristics associated with type-B people, but the bad rap going around about type-B men in Korea is that they are selfish, mercurial and absolutely useless as caring and devoted boyfriends. Personally I am not selfish even by the most restrictive definition of the term, but I don't know the part about "caring and devoted boyfriends" because I never (this is not a typo) ventured into dating scene.
According to a nationwide survey in South Korea conducted by Internet portal site xyinlove.co.kr, type-B men were considered to be the most difficult type to date and about 40 percent of women said they did not want to marry a type-B man. Source
So if you are in Korea and you are type B and you intend on dating Korean women then be sure not to reveal your blood type or better yet say A (all is fair in love and war). I wonder if they will go as far as requiring to see your blood test report before saying "Yes" to your bended knee proposal."
