A Cavallone subordinate; just as he serves as Dino's subordinate, he also served the former Cavallone boss. Romario would often be the first person Dino calls on, and is usually by Dino's side. He, like the rest of Dino's family, is aware of the fact that Dino is a major klutz when he is not around his family.

While Dino was training Hibari, Romario meets and becomes friends with Kusakabe, Hibari's second-in-command in the Disciplinary Committee.