The Japanese believe blood types impact specific personality traits, similar to the way some believe astrological signs indicate behaviors. This is similar to someone’s belief that your astrological sign can tell your personality. Some Japanese video game makers assign blood types to characters in games, so players can pick characters not only based on skills but also on personalities. For instance, if an aggressive competitor is needed, pick a character with Type O blood. But be careful, that character may also be arrogant and may not think before acting.