KETSUEKIGATA
In Japan, your blood type — A, B, O or AB — is treated the way a horoscope sign is treated in the West: a shared cultural shorthand for personality, splashed across magazines, dating profiles and TV. It is not science. It is, however, one of the most widely recognized personality frameworks on Earth. Read what your type is said to mean, and what the actual research found.
Every source agrees Type O gets along with almost everyone, Type AB’s strongest match is another AB, and A × B is the pairing that takes the most conscious effort.
A & O
Best match
A's best match. O's confidence and easygoing nature balance A's caution, and A's follow-through gives O's big ideas somewhere to land.
A & B
Takes more effort
The pair every source flags as the toughest. A's carefulness can read as controlling to B; B's spontaneity can read as unreliable to A. Workable, but it takes real effort from both sides.
AB & AB
Best match
AB's best match, and the single strongest pairing in the whole matrix. Two ABs are often described as reaching a rare level of mutual understanding, since so few people share this type's particular duality.
Full compatibility readings for every pairing are on each type’s own page.
The most serious scientific attempt to test blood-type personality theory — a peer-reviewed 2015 study of over 1,400 adults — found essentially no real link. Japan has also seen genuine social pushback against using blood type to judge people for hiring or dating, known as “bura-hara.” Read it the way you’d read a horoscope: worth a smile, not a basis for real decisions about people.
Ketsuekigata (血液型) is a mainstream Japanese pop-culture belief that your ABO blood type — A, B, O or AB — shapes your personality. It began with a 1927 paper and was revived as pop culture in the 1970s. It is genuinely widespread in Japan (magazine horoscopes, dating profiles, TV segments) but is not a validated psychological model.
Barely. The most serious attempt to test it — a peer-reviewed 2015 study of over 1,400 adults — found essentially no meaningful link between ABO type and personality traits. Treat it the way you would treat a horoscope: a fun cultural lens, not a scientific fact.
Bura-hara is the Japanese term for discrimination based on blood type — being judged for a job, promotion or relationship because of your ABO type. It is real and documented enough that Japan’s Health, Labour and Welfare Ministry has warned employers against asking about it. Type B carries the most documented stigma of the four types.
Type O pairs well with almost everyone. Type AB’s strongest match is another Type AB. The one pairing every source flags as the hardest work is A and B, where A’s caution and B’s spontaneity tend to clash — though every source frames it as effort, not doom.
Roughly A 40%, O 30%, B 20% and AB 10% — Type AB is the rarest of the four.