Ake no Emblem

There is a case of serial murder occurs in Runa's neighborhood. every victim is 18 years old women. All of them got murdered and had all of their blood sucked out. Everyone of them either has a scar or birthmark that looks like a crescent moon on their body. One of Runa's friend also got the same kind of Birthmark and got murdered. After Runa witnessed the scene and ran way from the murderer, her chronic headache got worse and a red crescent moon birthmark appear on her forehead and soon many incidents follow her upon this.