Personality Runs Deep: Japan’s Blood Type Theory

“What’s your blood type?” This question might be a little jarring, aside from in a medical setting. However, just as many people use astrology to structure their understanding of themselves and others, in Japan there is a popular belief that your blood type can determine your personality, strengths, weaknesses, and even dating compatibility. While there may not be much scientific evidence to support this theory it has taken Japan by storm.

The blood type theory can be traced back to 1916 when Doctor Kimata Hara first published the idea in a research paper. The theory reemerged in 1930 when psychologist Tokeji Furukawa released a similar thesis based on a study of 11 of his family members. The academic community quickly shot down the thesis but it remained a topic of interest. The idea was later forgotten but was revived in the 1970s by journalist Masahiko Nomi’s book outlining the blood type personalities and their relationships. The book became a best seller and by the 1980s the popularized theory appeared in music, TV shows, magazines, and more.

Despite no real scientific proof, the idea lingers in Japanese culture. According to a 2016 survey, about 99% of the population in Japan knows their blood type. However, only 29% of men and 45% of women trust the theory. Still, it has permeated many aspects of daily life, appearing in everything from books and movies to dating services and diet plans. While it offers a way to connect with others the concept has also been negatively spun.

“Bura hara” or “blood harassment” has become a problem as certain traits assigned to the blood types can be seen as detrimental and garner scorn from others. This can also happen when someone falls short of the expectations set by their blood type. The theory has also been used in job criteria and school entrance exams, giving unfair advantages to those with “preferable” blood types. In the 2000s this sparked an anti-blood type movement and even led to government intervention.

Blood Type Personalities

Type A:

Making up an estimated 40% of Japan’s population this is the most common blood type. They are earnest, responsible, sensible, patient, and well-organized. However, their need for order and sense of responsibility can make them easily stressed and stubborn.

Type B:

Making up only 20% of Japan’s population, they are often seen as the odd one out. They are passionate, creative, and strong-willed. They are active by nature and governed by their sense of curiosity. However, given that they march to the beat of their own drum they are sometimes seen as odd, erratic, selfish, and irresponsible. They often clash with type A.

Type AB:

While somewhat rare, making up only 10% of the population in Japan, they exhibit a blend of type A and B characteristics. They are said to be cool, calm, and collected, often allowing them workplace advantages. While they possess these A-like qualities they are still free-spirited dreamers who bounce between ideas and tasks based on their mood. Their complexity means that they can be viewed as indecisive or two-faced.

Type O:

The 30% of Japan’s population born with type O blood is said to be confident, self-determined, intuitive, optimistic, resilient, and flexible. They are often seen as mood-setters and natural-born leaders, so it is unsurprising that many of Japan’s Prime Ministers are a part of this group. However, type O are often workaholics and can seem self-centered or arrogant to others. 

Whether or not you believe in the blood type theory it can be a fun conversation starter and a great way to connect with people on your next trip to Japan!

About the author: 

Nadine Pryor

Nadine first became interested in Japan and Japanese culture after working with an exchange program at her university. After hearing so many wonderful things from the exchange students she worked with she was longing for a chance to see Japan for herself. That opportunity came to her in the form of the JET program where she spent 5 years on a small island in the beautiful prefecture of Okinawa. While living in this very rural community of just under 1,300 people she was lucky to experience a glimpse into some of Okinawa’s unique traditions and culture. In her free time, she traveled the main island of Japan as well as eastern Asia, seeking out the most delicious foods and exciting experiences. She currently resides in the United States but hopes to return to Japan in the future.