I want to ask about a manga?

I don't remember the name of it, but I remember a part of its name, the first part is The Legend or Legend of...something. It's about a boy who can see cracks on other people's body and there is also another girl who is a vampire in the manga. When they first met, the boy was terrified seeing that the girl is a creature that's not a human, and he cleaved the girl's body and she vanished into pieces. Then they met again, and she was still alive after that. She didn't kill him but told him about his special ability and told him that there are people who are the same as him. And by the way, she was very pissed off. She teached him about the most weak point of the body which once being thrust at can make the whole body breaks. And the girl is a vampire. So I want to know the name of this manga. Thank you in advance :)