Exploring the Ketsueki-Gata Personality Theory in Japan

Using one's blood type to predict character traits and compatibility with others originated from a philosophy known as Ketsueki-gata in Japan. The idea was first proposed by Takeji Furukawa, a Tokyo Women's Teacher's School professor, in 1927. In his paper 'The Study of Temperament Through Blood Type', published in the scholarly journal Psychological Research, he suggested that each 'type' showed distinctive characteristics; Type A are considered to be calm and trustworthy, B are passionate and robust, O are independent and decisive, while AB mysterious and artsy. While the work was initially met with much skepticism within the academic community due to the lack of rigorous testing or empirical evidence, it soon caught on in popular culture after an influential series of articles by journalist Masahiko Nomi, who had no medical background but wrote extensively about blood type theories, drawing heavily from Furukawa’s work. Ever since then, Ketsueki-gata has become deeply embedded into Japanese culture. People often make specific lifestyle choices, ranging from diet to dating, based on their blood type, which is also reflected in anime culture, where characters often have assigned blood types. However, it is noteworthy that while this belief is hugely popular, compelling certain companies to organize teams based on their employees' blood types, scientific consensus regards such correlations between one’s personality and blood group as pseudoscientific and lacking empirical credibility so far. Further reading: 'You Are Your Blood Type': The Pseudoscience That Persists In Japan by Nathaniel Scharping (2019); 'A Culture of Type' by Naho Kitano in Asian Medicine Journal (2008); 'The Study of Temperament Through Blood Type' by Takeji Furukawa in Psychological Research (1927).