Nero Gladius(ネロ・グラディウス; Nero guradiusu), also known as the traitorous knight of the Crimson maiden, is a supporting character in Highschool DxD: Яe-birth. The second Knight in Nemesis Gremory's Peerage, he's both Aria's and Nemesis's boyfriend/lover, ichijou's second mentor and one of the bodyguards of Alice Gremory.