The Chasing World 4 by Mari Asato

4.30

One day, it's decided that all people with blood type B have to be killed. There are people in black costumes who chase after and kill everyone with blood type B. Tsukasa is one of those people. Together with her friend Yui she tries to stay alive and staying alive means running because hiding isn't a solution. On the hunt, they meet Masaharu and together they decide to fight against those black costumed creatures.