Biagio Busoni is an Italian bishop in the Roman Catholic Church, wielding authority to command one thousand soldiers for his projects. He wears ornate, heavily decorated clothing lacking individual traits: primarily white robes with gold accents, extensive golden jewelry, multiple small crosses adorning his chest, and a small red cap. His personality exhibits ruthless devotion to the Roman Catholic Church's glory, considering its supremacy paramount. This fanaticism drives him to sacrifice the entire Queen's Fleet to preserve the Church's reputation. Supreme arrogance defines his demeanor, persisting through captivity and interrogation. He displays cruelty through defiance toward captors and disregard for failing subordinates. During the La Regina del Mare Adriatico Arc, he oversees the modification of the "Queen of the Adriatic Sea" from a Venice-specific weapon into one capable of targeting Academy City to destroy the Science Side. He commands the Agnese Forces as punishment for their prior failures, forcing them into servitude aboard the fleet. His plans unravel when Touma Kamijou and Orsola Aquinas accidentally board the vessel, aiding Agnese Sanctis's escape. After an Amakusa Church attack, Busoni fights Touma but is defeated. Captured by the Anglican Church, he is imprisoned in the Tower of London alongside Lidvia Lorenzetti. In the Document of Constantine Arc, he undergoes interrogation by Stiyl Magnus and Agnese Sanctis while detained. Sleep deprivation cracks and dries his skin and hair, yet his arrogant defiance remains. He challenges Stiyl to employ torture devices, boasting of demonstrating "true piety." Threatened with lethal information extraction, he responds with silence and irritated clicks. Lidvia later negotiates an information exchange for prisoner release without his consent, revealing God's Right Seat secrets to secure Oriana Thomson's freedom while he remains incarcerated. His magical abilities manipulate multiple crucifix necklaces, releasing diverse powers through symbolic meanings: - **St. Margaret's Crucifix:** Expands wielded or thrown crucifixes to three meters long and forty centimeters thick via incantation: "The Cross reveals the rejection to evil," invoking Saint Margaret's dragon escape. - **Weight of the Cross:** Multiplies crucifix weight several thousandfold via intensified gravity, activated by: "The weight of the Cross corrects the haughty." Thrown crucifixes become cannonball-like projectiles, drawing from Saints Lucia and Christopher. - **Simon Carrying the Cross:** Forces enemies to bear immense weight concentrated from surrounding people and equipment, executed by raising a crucifix overhead while incanting: "Simon bears the cross of the Son of God." This manifests as downward pressure, invoking Simon of Cyrene's biblical role. His narrative concludes with ongoing imprisonment in the Tower of London.