People in most parts of the world don't think about their blood group much, unless they have an operation or need a transfusion. But in Japan, whether someone is A, B, O or AB can have implications for life, work and love. There is a widespread belief that blood type determines personality. Blood typecasting is as common as horoscopes in the West. "This particular thing about blood types is a clever way of telling people what you think about them, but indirectly," said Jeff Kingston of Temple University, Japan Campus. "Here people don't like to be upfront and open about their opinions. So if you can hide behind blood types you can then tell someone indirectly what you think about them."