Most people don’t give much thought to their blood group, unless they have an operation or an accident and need a transfusion. But in Japan, blood type - or ketsueki-gata - is an enormously popular way of defining temperament and personality, and has big implications for life, work and love.

Discussion of blood types is popular in women's magazines as a way of determining compatibility in relationships. Morning television shows and daily newspapers feature blood type horoscopes. Young Japanese also commonly exchange blood types on first meeting. Anime, manga and video games often mention characters' blood types and special shampoo, bath salts and other products are marketed for different blood types.

Type A are believed to be earnest, sensible, responsible; type B selfish, irresponsible, unpredictable. Job interviews can be determined by blood type and it even affects politics. A former prime minister put the fact that he was a type A in his official profile on the internet. A Japanese minister recently resigned, blaming his failings on his blood type B.

(Image: Vials of blood. Credit: Chung Sung-Jun/Getty Images)