The character often referred to as Capo or simply Boss is the leader of the Mamma Aiuto gang, a group of air pirates operating across the Adriatic Sea. He is a large, imposing figure with a loud and authoritative presence that matches his role as the head of a feared criminal organization. Despite his fearsome reputation and ego, which is matched only by his bravado in wanting to defeat the protagonist Porco Rosso in combat, his personality is not entirely harsh. Behind his gruff exterior, he displays a notable gentleness, particularly towards the two main female characters, the singer Gina and the young mechanic Fio Piccolo.

The Boss's role in the story is primarily that of an antagonist, though he is not a truly villainous figure. He and his gang serve as the initial threat that sets Porco Rosso's adventure in motion. One of his first significant actions is the kidnapping of a group of schoolgirls from a cruise liner. While this act puts the children in peril, a crucial aspect of his character is revealed in this moment: he explicitly refuses to harm his captives and also refuses to separate the girls from their friends, demonstrating a personal code of honor. After Porco damages the gang's large flying boat, the Dabohaze, with machine gun fire, the Boss promptly surrenders, exchanging the hostages and their stolen gold for safe passage.

His motivations are largely driven by a desire for revenge against Porco Rosso, whom he despises and calls the stinkin pig, and a need to restore his gang's bruised ego after repeated defeats. This leads him to ambush Porco in his own hideout upon the pilot's return to the Adriatic with Fio. However, his respect for Fio is so great that when she passionately lectures the pirates about the honor of seaplane pilots, he and his men decide not to destroy Porco's newly rebuilt aircraft. Instead of acting on their original vengeful plan, the Boss's role shifts. He becomes a facilitator for the final act of the story, organizing a grand aerial duel between Porco and his rival, the American pilot Donald Curtis, and presiding over the event as a master of ceremonies of sorts.

The Boss’s key relationships define his character arc. His relationship with Porco evolves from straightforward enmity to a kind of grudging respect, as he is present as an observer for their final duel. His interactions with Fio are particularly significant; the tough pirate leader is swayed by her determination and engineering talent, treating her with an uncharacteristic softness and even ending up in a comical commemorative photograph with just her after everyone else is knocked down before the shutter clicks. His bond with Gina is also marked by this same gentle treatment, indicating a chivalrous side that the pirates reserve for women.

Throughout the film, the Boss does not undergo a dramatic personal transformation, but his role shifts from a primary antagonist to a more neutral and even supportive figure. He is a classic example of a lovable rogue or a minor villain in the tradition of Hayao Miyazaki's films; he is an obstacle for the hero, but he is ultimately a man of his word who adheres to his own simple principles. In the epilogue, set years later, he is shown as an older man who has lost most of his hair, enjoying a peaceful retirement at the Hotel Adriano alongside his former gang members, suggesting that he has left his pirating days behind. As the leader of the Mamma Aiuto, his notable abilities lie not in personal combat, but in his command over a well-organized and effectively feared pirate gang, his influence over the Adriatic skies, and his capacity to organize large-scale events like the final duel.