Nero is a lead character of Devil May Cry 4, marking his first appearance in the franchise and sharing a main role with series protagonist, Dante. An orphan that was adopted by the Order, he has grown up to be a Holy Knight in the Sparda-worshipping religion known as the Order of the Sword. He tends to not get along well with others and prefers to work alone, so he is usually given the Order's "special assignments." He wields a sword named Red Queen, a revolver called Blue Rose and the "Devil Bringer" powers of his right arm. By defeating various Demons, Nero is able to increase the power of the Devil Bringer. Nero comes into possession of Yamato, Vergil's sword, which allows him a Devil Trigger which summons a Devil avatar to fight with him.
Throughout Devil May Cry 4, Nero perceives Dante as the enemy, but as the story progresses he realizes that it's the Order who is organizing their own agenda. Nero pivots his role as a Holy Knight to a renegade searching for answers, then into a vengeful demon slayer when the Order captures Kyrie. In the end, Nero and Dante join forces to defeat the Savior, saving Kyrie in the process. Nero and Dante part on good terms with Dante entrusting Nero the sword, Yamato, that was originally his brother's.