Ketsueki-gata: The History of Blood Type Personality in Japan
Updated 2026-11-07T00:00:00.000Z
In Japanese, blood type personality is called ketsueki-gata (血液型), literally “blood type”. Asking someone’s blood type is as ordinary as asking their star sign in other countries, and morning TV shows have long run daily blood type fortunes.
1927: Takeji Furukawa
The idea is usually traced to Takeji Furukawa, a professor at a women’s teacher-training school in Tokyo. In 1927 he published a paper, “The Study of Temperament Through Blood Type”, based on a small survey of his acquaintances and students. He suggested that type O and B people were more active and type A people more passive.
His work drew interest in the 1930s but was criticised by other researchers for its tiny samples. By the time of his death in 1940, the theory had mostly faded from scientific discussion.
1970s: Masahiko Nomi and the boom
The modern craze began in 1971, when broadcaster and writer Masahiko Nomi published a bestselling book on blood type and compatibility. Nomi had no medical or psychology training, but his lively writing and confident claims sold millions of copies. He followed it with many more books, and his son Toshitaka Nomi continued the work.
From then on, blood type appeared everywhere in Japanese media: magazines, manga character profiles, dating advice and even product marketing. In the 2000s a series of four books, one for each type, sold over five million copies combined.
Blood type harassment
The popularity had a downside. People were sometimes judged by blood type at school, at work or in relationships. This came to be called bura-hara (ブラハラ), short for “blood type harassment”. In 2004, Japan’s broadcasting ethics body BPO asked TV stations to avoid programmes that encourage blood type discrimination.
How common each type is in Japan
| Type | Share (approx.) |
|---|---|
| A | 40% |
| O | 30% |
| B | 20% |
| AB | 10% |
With type A the largest group, it is perhaps no surprise that the A stereotype (diligent, harmonious, careful) matches traditional ideals of Japanese social behaviour.
Today
Blood type remains a familiar topic in Japan, though younger people, as in Korea, increasingly use MBTI. Scientific reviews, including large Japanese studies, have found no meaningful link between blood type and personality.