In North America, knowing your Sun Sign, or astrological sign, is a very common practice. From it people could read mythologies on their personalities, do match-making and get predictions for their futures via horoscopes. In Japan, however, the common practice is knowing your blood type.
Blood type mythology allows people to determine a person's personality traits and dispositions. It originated through actual psychological studies from the 50s to 70s. Over time it became a very influential method to determine what sort of person someone was and is taken more seriously by the majority than how Sun Signs can vary from nonsense, a hobby to a way of life.
Haruka's blood type is B and with that comes expected traits to her personality as well as calculations on what would be the perfect blood type for her partner in life to have!
♅ Like to go their own way
♅ Do what they want without considering other people’s feelings, rules and customs
♅ Happy-go-lucky and masters of breaking rules
♅ Optimistic
♅ Friendly and open their heart to anybody
♅ Not pretentious
♅ Afraid of being alone
♅ Get lonely easily
♅ Quick to adapt
♅ Flexible thinkers
♅ Pragmatists
♅ Don’t chase a dream much
♅ Like to play
♅ Love festivals and parties
♅ Have been in love many times
♅ Don’t get heart-broken over lost love
♅ Partner who is type A – Type A person is always willing to help type B person; however, they get tired of each other easily. Type A often complains to type B.
♅ Partner who is type B – Both of them are not careful, so they may do things that are off the rail.
♅ Partner who is type AB – They attract each other and they may quickly start a relationship. They love each other very much.
♅ Partner who is type O – They can understand each other easily. Type O person covers for type B person’s bad points. They are a great match for friendship.
Sources:
B Blood Type. Japanvisitor.com. Japanese Culture: Blood Types.