The System That Granted Me The Powers To Kill Vampires

A world where Vampires feed on human flesh and blood. Some can deceive you into thinking they are human but they are not. Rick is an ordinary boy who almost dies until in his eyes a screen flashes [You have now been granted the system] [Error...Error] [Kill all vam....Error] Even if Rick has the system that grants him information and powers to kill vampires and rank up to be the best hunter, even with the system He is still not safe from the vampires destroying towns that is far stronger than him. How will Rick use the system that he is granted from the unknown? Will he use it for the wrongdoings? Will he use it to save people?