Biagio Busoni occupies the position of bishop in the Roman Catholic Church, commanding a military force of 1,000 soldiers for his operations. His central mission involves repurposing the "Queen of the Adriatic Sea"—a weapon originally engineered to destroy Venice—into a mobile platform capable of targeting Academy City. This initiative underscores his ruthless pragmatism, as he prioritizes the Church’s strategic interests above human cost, readily expending subordinates’ lives to shield its image.

After his schemes collapse, he is incarcerated within London Tower alongside collaborator Lidvia Lorenzetti. Subjected to relentless questioning by Stiyl Magnus and Agnese Sanctis, his body weakens from prolonged sleep deprivation, though his defiant posture remains unbroken. He mocks torture attempts, daring interrogators to probe his limits. Conversations expose his contempt for former underlings like Agnese Sanctis, coupled with unyielding opposition toward the Church’s enemies.

Biagio wields cross-based thaumaturgy via layered crucifix necklaces. His combat methods involve manipulating sacred artifacts into three-meter crucifixes, amplifying their mass through gravitational distortion, and inflicting crushing physical penalties on foes. These spells derive potency from Christian lore, channeling narratives like St. Margaret’s draconian imprisonment and Simon of Cyrene’s forced cross-bearing.

Visually, he is defined by opulent ecclesiastical vestments lacking distinguishing physical traits, befitting his role as an ephemeral antagonist. Post-capture, he fades from prominence, making no substantive appearances in later narratives beyond confinement.