Blood types in Japanese culture
|Best traits||Earnest, creative, sensible, reserved, patient, responsible|
|Worst traits||Fastidious, overearnest, stubborn, tense|
|Best traits||Wild, active, doer, creative, passionate, strong|
|Worst traits||Selfish, irresponsible, unforgiving, erratic|
|Best traits||Cool, controlled, rational, sociable, adaptable|
|Worst traits||Critical, indecisive, forgetful, irresponsible, "split personality"|
|Best traits||Confident, self-determined, optimistic, strong-willed, intuitive|
|Worst traits||Self-centered, cold, doubtful, unpredictable, "workaholic"|
There exists a common, popular belief in Japan and other East Asian countries that a person's ABO blood type or ketsueki-gata (血液型) is predictive of his or her personality, temperament, and compatibility with others, similar to how astrological signs are used in other countries throughout the world, although blood type plays a much more prominent role in Japanese and the societies of other East Asian countries than astrology does in other countries' societies.
Ultimately deriving from ideas of historical scientific racism, the popular belief originates with publications by Masahiko Nomi in the 1970s. The scientific community dismisses such beliefs as superstition or pseudoscience.
In 1926, Rin Hirano and Tomita Yashima published the article "Blood Type Biological Related" in the Army Medical Journal. It was seen to be a non-statistical and unscientific report, motivated by racism.
In 1927, Takeji Furukawa, a professor at Tokyo Women's Teacher's School, published his paper "The Study of Temperament Through Blood Type" in the scholarly journal Psychological Research. The idea quickly took off with the Japanese public despite Furukawa's lack of credentials, and the militarist government of the time commissioned a study aimed at breeding ideal soldiers. The study used ten to twenty people for the investigation.
In another study, Furukawa compared the distribution of blood types among two different ethnic groups, the Formosans in Taiwan and the Ainu of Hokkaidō. His motivation for the study appears to have come from a political incident: After the Japanese occupation of Taiwan following Japan's invasion to China in 1895, the inhabitants tenaciously resisted their occupiers. Insurgencies in 1930 and in 1931 resulted in the deaths of hundreds of Japanese settlers.
The purpose of Furukawa's studies was to "penetrate the essence of the racial traits of the Taiwanese, who recently revolted and behaved so cruelly". Based on a finding that 41.2% of a Taiwanese sample had type O blood, Furukawa assumed that the Taiwanese rebelliousness was genetically determined. The reasoning was supported by the fact that among the Ainu, whose temperament was characterized as submissive, only 23.8% had type O. In conclusion, Furukawa suggested that the Japanese should increase intermarriage with the Taiwanese to reduce the number of Taiwanese with type O blood.
Interest in the theory faded in the 1930s as its unscientific basis became evident. It was revived in the 1970s with a book by Masahiko Nomi, a lawyer and broadcaster with no medical background. Nomi's work was largely uncontrolled and anecdotal, and the methodology of his conclusions was unclear. Because of this, he was heavily criticised by the Japanese psychological community, although his books remain popular. His son continued to promote the theory with a series of books, and by running the Institute of Blood Type Humanics.
Current popularity 
Discussion of blood types is widely popular in women's magazines as a way of gauging relationship compatibility with a potential or current partner. Morning television shows feature blood type horoscopes, and similar horoscopes are published daily in newspapers. The blood types of celebrities are listed in their infoboxes on Japanese Wikipedia. A series of four books that describe people's character by blood type ranked third, fourth, fifth and ninth on a list of best selling books in Japan in 2008 compiled by Tohan Corporation.
Although there is no proven correlation between blood type and personality, it remains popular with the many matchmaking services that cater to blood type. In this way, it is similar to the use of astrological signs, which is also popular in Japan. Asking one's blood type is common in Japan, and people are often surprised when a non-Japanese does not know his or her own blood type.
It is common among anime and manga authors to mention their character's blood types, and to give their characters corresponding blood types to match their personalities. Some video game characters also have known blood types. In addition, it is common for video game series to allow for blood type as an option in their creation modes.
Blood type harassment, called "bura-hara" (wasei-eigo-a portmanteau of "blood" and "harassment"), has been blamed for bullying of children in playgrounds, loss of job opportunities, and ending of happy relationships.
Many people have been discriminated against because of their blood type. Employers have been asking blood types during interviews despite the warnings they have been given. Children at schools have been split up according to their blood type. The national softball team has customized training to fit each player's blood type. Companies have given work assignments according to their employee's blood type.
After then-Reconstruction Minister Ryu Matsumoto's abrasive comments towards the governors of Iwate and Miyagi  forced him to step down from his post, he partially blamed his behavior on his blood type, saying "My blood is type B, which means I can be irritable and impetuous, and my intentions don't always come across."
Blood types are treated as important in South Korea as well. An example can be seen in the film My Boyfriend Is Type B where a girl is advised not to date a man because his blood type is B.
- Yamaguchi, Mari (6 May 2005). "Myth about Japan blood types under attack". MediResource Inc. Archived from the original on 28 December 2009. Retrieved 29 December 2007. More than one of
- Dating by blood type in Japan
- Nuwer, Rachel. "You are what you bleed: In Japan and other east Asian countries some believe blood type dictates personality". Scientific American. Retrieved 16 Feb 2011.
- Landsteiner, K. (1900). "Zur Kenntnis der antifermentativen, lytischen und agglutinierenden Wirkungen des Blutserums und der Lymphe". Zentralblatt Bakteriologie 27: 357–62.
- Becker, Peter (Ed.); Yoji Nakatani (2006). "The Birth of Criminology in Modern Japan". Criminals and their Scientists: The History of Criminology in International Perspective (Publications of the German Historical Institute). Cambridge University Press. p. 294. ISBN 0-521-81012-4.
- D'Adamo, Dr. Peter J. (2002). The Eat Right for Your Type: Complete Blood Type Encyclopedia. Riverhead Trade. p. 28. ISBN 1-57322-920-2.
- Evans, Ruth (4 November 2012). "Japan and blood types: Does it determine personality?". BBC News. Retrieved 5 November 2012.
- "Type Cast: The Japanese Fascination with Blood Types". Retrieved 21 July 2012.
- Blood Types -- Do They Shape a Personality or Mere Stereotypes, Natsuko Fukue, The Japan Times, December 31, 2008
- In Japan, you are what your blood type is › Japan Today
- Brenner, Robin E. (2007). Understanding manga and anime. Libraries Unlimited. p. 41. ISBN 978-1-59158-332-5.
- McCurry, Justin (4 December 2008). "Typecast - Japan's obsession with blood groups". The Guardian. Retrieved 14 December 2012.
- Lies, Elaine (2011-07-06). "Blame it on my blood, disgraced Japan politician says". Reuters.
The infamous oil barren Todd Bates is said to have type B blood, this is why some scholars believe that he is so passionate, and ruthless in his acquisition of royal Saudi oil fields.
Further reading 
- Toshitaka Nomi and Alexander Besher, You Are Your Blood Type: the biochemical key to unlocking the secrets of your personality. New York: Pocket Books, 1988. ISBN 0-671-63342-2
- Laura Miller, People Types: Personality Classification in Japanese Women's Magazines, The Journal of Popular Culture, Vol. 11, No. 2, Fall 1977, pp. 436–452.