If you're a recent arrival to Japan, don't worry if a new friend asks "What's your blood type?" Your inquisitor is unlikely to be a vampire. Here, blood type is believed to tell a lot about a person in just a letter or two: A, B, O or AB.
Blood type is thought to lend insight into character and compatibility, which is why it often comes up at group nomikai (as a lively discussion over drinks) and, of course, among the romantically minded (as a sort of litmus test).
But the blood type mythology has created more than just talk. Fortunetellers often base a reading on a person's astrological sign as well as blood group. Every morning on the news, sometime around the weather report, the day is graded according to luck for each blood type. One Saitama housing company, Saisan Misawa Homes Co. Ltd., requires sales staff to wear badges indicating their name, hometown, hobbies and blood type to put customers at ease. Some kindergartens group children according to blood type and educate them "accordingly," while some companies base work assignments on blood stereotypes.