What’s your blood type? (あなたの)血液型は何型? ((あなたの)けつえきがたはなにがた? Anata no ketsueki-gata wa nani-gata?)

If you are living in Japan, you will get asked this question at least once by a Japanese person. For foreigners, this is such a baffling question! Most of the time, foreigners do not even know their blood type unless it is necessary for some medical health check or a blood transfusion.

In Japan it is not uncommon for people to know their own blood type and to ask each other what it is. From the day they are born, most Japanese will likely know their blood types and will casually tell and ask their peers.

Why is Japan so obsessed with knowing and understanding their and other’s blood types?

In Japan, there is a belief that your blood type determines your personality and how compatible you are with others which is almost comparable to horoscope readings in western cultures.

It is a pseudoscientific belief that started in 1931 by Furukawa Takeji (1891 – 1940) who proposed there was a link between blood types and personalities after working in a high school departement that observed the temperamental differences between candidates. He published a paper in 1927 called “The Study of Temperament Through Blood Type” which stated that personality is determined by people’s blood type. His work became so popular that the Japanese Army began to research on this subject and in some cases they had separated the new soldiers according to their blood types to give the specific training.

After World War II, much of this theory had been forgotten until Masahiko Nomi, a journalist with no medical background, revived the theory by publishing a book. His works demonstrated significant statistical data in the blood type theory, but his methods and conclusions were unclear and came under high scrutiny and criticism from Japanese psychologists. With that being said, his son Toshikata Nomi, continued to promote his father’s theory by writing various books and establishing the Institute of Blood Type Humanics.

Nowadays, there are multiple books and fortune tellings on blood types and personality. There are diet books which tell what type of food is best for your blood types, match making books to see who you are most likely to be compatible with, blood type fortune tellings on morning news corners, etc. Blood type and their relationship with personality is so common that it is sometimes used as an excuse for their behaviours at times. For example, “My blood type is A, I am always serious and is keen on doing it the right way which is why I am a neat freak.” sounds a little OCD…

The different blood types and their personalities

Blood Type A – The Farmer Blood Type B – The Hunter Blood Type AB – The Humanist Blood Type O – The Warrior
Calm Individualists Cool Natural Leaders
Responsible Strong Controlled Loyal
Punctual Optimistic Rational Passionate
Perfectionist Flexible Sociable Self Confident
Patient Wild Popular Ambitious
Sensitive Unpredictable Critical Vain
Obsessive Forgetful Aloof Jealous
Overcautious Irresponsible Indecisive Arrogant
Stubborn Self-centred Worried about perception from others Ruthless
Unable to Relax Impulsive Unforgiving Insensitive

In Western cultures, blood type may seem irrelevant when choosing friends or partners, but in Japan, it plays somewhat of an important role. A stereotypical judgement is made in order to see if that person will be compatible with them or not. Especially when it comes to looking for love, blood type plays such a significant role in order to judge their relationship as a couple and for future martial purposes.

I have listed a quick compatible affiliation with different Blood Types.

Blood Type A Compatibility

  • Type A : Share common traits, but since both are high strung and may be too similar, they could get on each other’s nerves.
  • Type B : Envies type B’s optimistic, carefree personality, but may get worried about their overly relaxed attitude.
  • Type AB : Very compatible as Type A can easily rely on Type AB for good advice and support.
  • Type O : May feel very protected by Type O, but their compatibility decreases when Type A discusses every little thing.

Blood Type B Compatibility

  • Type A : Type A will always be willing to help, but their relationship mat strain as they can get tired of each as Type A often complains to Type B.
  • Type B : Both are very flexible and wild when together which may be fun at times, but can be a little risky without careful thought.
  • Type AB : Very compatible with each other and can quickly start a relationship together.
  • Type O : They are very compatible when it comes to friendship as they seem to understand each other well and with Type O covering for Type B’s negative traits.

Blood Type AB Compatibility

  • Type A : They can have a respectable and compassionate relationship with each other but may often have arguments.
  • Type B : Very compatible with each other and can have a deep sense of connection with each other.
  • Type AB: Can be compatible and open their hearts to each other, but they should be neither too close or too far away from each other.
  • Type o : They have very good business compatibility and can produce ideas and things with each other.

Blood Type O Compatibility

  • Type A : They are quite compatible with each other with Type O taking the protective lead in the relationship.
  • Type B : Both are able to openly talk and have a comfortable relationship with each other but the mood may get affected and confused by Type B’s mood personality.
  • Type AB : Their thinking way is quite similar so they are often compatible until they start being competitive with each other.
  • Type O : Although they are the same blood type, they do not often understand each other on basic terms and may feel alienated by each other. They do not have the best compatibility when it comes to love so it is best not to get too close to each other.

All this information sounds a little complex and hard to remember, but just like Horoscopes, it’s just a pseudoscientific theory that a lot of Japanese people have fun with. Although it is not scientifically proven, yes some people will base stereotypical judgement on each other, but others just know it for fun. Of course there are personality traits that mix-matches with whatever blood type you may be and you may be compatible with what blood types that tests say you are not compatible with. The best thing to do with all this info is to take it lightly like a horoscope and just play with it!