If you are a reader of manga, you may have noticed that character profiles, in addition to including basic information like name and date of birth, also list blood type. And you may be wondering, why? For many, it may seem odd or unnecessary to be provided a random medical fact about a character. But in Japan, blood type is seen as a valuable detail and signifier of personality.
Blood type personality theory is a popular belief in Japan (and some other East Asian countries), applied in the same way that astrological signs or other personality models (such as the Myers-Briggs or the Enneagram) are used in the west. Japanese morning shows and newspapers will have daily blood type horoscope segments, celebrities will always list blood type on their profiles, and it is also commonly used as a compatibility indicator by matchmaking services. Growing up in Japanese culture, blood type was very often a part of the conversation around me and continues to be a large part of how I see and understand personality types.
You may be thinking, “But there are so few blood types!?” And it’s true, every other personality indicator out there, at least that I can think of, has significantly more categories than the four blood types (positive/negative is not a factor here). In my experience, though, conversations about blood type and personality will not be solely about one’s own blood type, but will also consider blood types of family members. For instance, being a type A person from a family of all type A people is different from being a type A person from a family with a combination of type A and type B people, and so on. (Though blood type personality theory is not supported by scientific fact, it can be somewhat helpful to think back on phenotype vs. genotype and those Punnett squares you learned in high school biology.) Additionally, people will often think of blood type as working in conjunction with other personality indicators like one’s astrological sign, Chinese zodiac, and dõbutsu uranai (a Japanese animal horoscope also based on birthdate).
In manga and anime (and sometimes other forms of fiction), assigning blood types to characters acts as a kind of shorthand that provides audiences with a little bit of basic insight into who those characters are and how they might interact with others. In cases when blood types are not given, it is common to find people speculating and discussing theories based on the characters’ traits and behaviors.
So now that we’ve covered the why behind blood types in character profiles, what does it all mean? Below are descriptions of the main personality characteristics of each blood type, as well as some examples of manga characters with those blood types. Obviously, not all characters (or real people) will fall into these different categories perfectly (as with any other personality indicators), but these can provide a rough foundation for how characters are established and shaped.
People with A blood type are often considerate and kind hearted. They are also deliberate and well thought out in their actions — the type to follow directions to the letter — always moving with great care and finishing what they start. They are straightforward and trustworthy, with a very strong sense of good/bad and right/wrong. This, however, can also mean they tend to dislike or have a hard time understanding unconventional methods or ways of thinking, sometimes leading to stubbornness and inflexibility. Type A people sometimes hold themselves back due to their worried and risk-averse nature.
People with B blood type have strong, magnetic personalities that make them stand out and draw others in. They are incredibly individualistic, independent, and tend to pave their own paths, often opposing societal norms and cultural trends in favor of their own beliefs and interests. Type B people tend to act on instinct and emotion instead of logic and reason, and are very resilient in the face of pressure and challenges. Naturally curious, when they become interested in something, they will dive deep and learn everything they can about said subject or topic. Despite these passionate and even obsessive tendencies, they are also quick to lose interest and will abandon things fairly easily. They can be self-centered and sometimes have difficulty accommodating people around them. They often have extreme emotions, and their moods can be easily and suddenly swayed by external forces, causing others to sometimes perceive them as volatile.
People with O blood type are generally easygoing and sociable, with a strong ability to read a room. They can get along with anyone and have excellent leadership skills. They approach situations with a great level of calm and don’t sweat the small stuff, though this can also lead to a lack of thoroughness and a tendency to overlook details. These are the type of people who will skim through directions once, proceed with extreme (but false) certainty, and then shrug off any errors made along the way. They love and thrive on compliments, but can easily become overly confident or even smug.
Some examples of characters with O blood type include Izuku Midoriya (My Hero Academia), Usagi Tsukino/Sailor Moon (Sailor Moon), and Makoto Kino/Sailor Jupiter (Sailor Moon).
People with AB blood type usually have very free-spirited and lighthearted personalities. They are likely to have great talent or genius, and can often be perceived as enigmatic. They generally possess various combinations of the qualities of both A and B blood types, which can sometimes result in others believing them to be disingenuous or difficult because of their seemingly conflicting characteristics. They can be quite sensitive and do not like conflict. Type AB people are not easily able to match their energy levels to a situation, and especially have trouble reigning themselves in when excited or frenzied. Their internal experience is quite rich, as they tend to be able to carry multiple trains of thought simultaneously or move through them extremely quickly, though this can also lead others to find conversations with them choppy and haphazard.
Some examples of characters with AB blood type include Sasuke Uchiha (Naruto), Yuno (Black Clover), and Rei Hino/Sailor Mars (Sailor Moon).
Next time you pick up a new manga (or revisit a favorite), try noting and keeping the blood types of the characters in mind as you move through the story. As with any other personality typing methods, remember that blood type personality theory is not meant to be 100% accurate or definitive (and, again, is not based in hard, scientific fact), but it can be a fun lens to look through and provide a rough framework for recognizing character traits.
If you’re into personality typing in general, we’ve got tons of great stuff in our archive! Whether you’re interested in Myers-Briggs, the Enneagram, or want monthly reading horoscopes, we’ve got your bases covered!