Tansaikigou: Sec Life, Monochrome Cube

Synopsis en anglais

Main character's parents get killed on the Christmas night by some red shadow. Eleven years later a wave of mysterious murders occurs at the town. All the witnesses can only say that killer just disappears in the air. Main character already knows by his past memory that the murders are caused by a vampire. He takes a sword and stands on the path of revenge. Mysterious girls join him in this quest.