There is no special relationship between blood type and personality, and it is not a medical category. There are many people who are concerned with blood type and personality, astrology and personality, zodiac sign and personality, and other studies on personality and character, and there are also many books on this subject. Many people summarize, analyze, and count similar traits through personality traits, such as A blood type as career type, and maybe A blood type has such traits, but personality and blood type are not necessarily related. From a medical point of view, people with type O blood have a higher incidence of peptic ulcer disease compared to other blood types, but there is no special study on the relationship between blood type and personality, and there is no special inevitable connection.