Blood Type-Personality Analysis

A person's blood type is believed to be predictive of his or her personality in Japan, even though there is no scientific proof on it.

Type A:
Best traits; Earnest, creative, sensible, perfectionists, calm
Worst traits; Fastidious, overearnest

Type B:
Best traits; Artistic, active, spontaneous, individualists
Worst traits; Selfish, irresponsible

Type AB:
Best traits; Cool, controlled, rational
Worst traits; Critical, indecisive, boring

Type O:
Best traits; Agreeable, sociable, optimistic, self confident
Worst traits; Vain, jealous, arrogant

Asking one's blood type is common in Japan, which means indirect question to measure the personality. Bloodtype traitscope is popular in particular for Japanese woman to predict compatibility with a potential partner, which is similar to the use of astrological signs in the West. But they do not necessarily follow the direction, because love is blind.
For more information --> Japanese Blood Types and Personality
                                   --> Personality Traits By Blood Type