What's the significance of revealing a character's blood type? A lot of Anime shows will reveal the blood type of one or more of the main characters:




What's the significance of it? What purpose does it serve?
Where did it come from?
Blood type in Japan is associated with temperance or personality. On Facebook in Japan, as well as Wikipedia and matchmaking sites, blood type can be listed. Many horoscopes and matchmaking services also use blood type to match people together.

According to Wikipedia:


  It is common among anime and manga authors to mention their character's blood types, and to give their characters corresponding blood types to match their personalities. Some video game characters also have known blood types. In addition, it is common for video game series to allow for blood type as an option in their creation modes.


The associated personality traits (from the chart here):


A

Better traits: Earnest, creative, sensible, reserved, patient, responsible
Worse traits: Fastidious, overearnest, stubborn, tense

B

Better traits: Wild, active, doer, creative, passionate, strong
Worse traits: Selfish, irresponsible, unforgiving, erratic

AB

Better traits: Cool, controlled, rational, sociable, adaptable
Worse traits: Critical, indecisive, forgetful, irresponsible, "split personality"

O

Better traits: Confident, self-determined, optimistic, strong-willed, intuitive
Worse traits: Self-centered, cold, doubtful, unpredictable, "workaholic"