Not my type
Many Japanese people believe that your blood type indicates something about your character, much like horoscopes in the West.
There's little or no scientific basis for this, but the general beliefs about blood type are:
Type A - calm, composed, level-headed, serious, reliable, trustworthy. Appearing aloof or superior, they are often surrounded by people of their own type, as they find it difficult to rely on other types. Most Japanese people are Type A.
Type B - cheerful, enthusiatic, excitable, self-involved, capricious. They always appear bright and full of energy, but they are often hiding an inner lack of confidence.
Type O - carefree, generous, popular, strong-willed, adaptable to new things. They are the diplomats, who maintain group harmony but occasionally make big mistakes by not being careful enough. Most Americans are Type O.
Type AB - sentimental, considerate, cautious. There are two sides to AB types: their behaviour is significantly less direct with "outside" people than with "inside" people who they are comfortable with.