Konata's Favorite

any one know the name to this story? it in a world were only the strong are allowed to live the mc is considered weak until one day his grandmother dies before his eyes by the hands of his father as she had been caught by some bandits. in a fit of rage he unlocks his power and attacks his father. the father pleased that the boy finally has some use sends him to this school to spy on it. there are also vampires and demonds in the world he is apart of the beast clan