Barone initially rules as a mazoku overseer in Rome, allowing humans to fight for freedom yet never facing defeat himself. His demeanor remains distant and aloof, frequently justifying solitude with claims that others cannot comprehend him. He exhibits a dual nature: a refined side displayed through gestures like combing his hair with Battle Spirits cards, contrasted by savage aggression in combat. This duality shifts when he encounters Dan, a human Brave user, sparking fascination that drives Barone to defy orders and challenge Dan directly. Though victorious in their first duel, Barone reels when Dan defeats his cherished spirit Strike-Siegwurm, igniting a transformative perspective shift.

After losing to Dan and rebelling against mazoku leadership, Barone suffers betrayal by Triple Alliance member Zazie, who frames him for treason with fabricated evidence. Banished by Queen Gilfam, he contemplates Dan’s ideals during exile and rescues a human boy during an earthquake. Immersed in human recovery efforts, his internal turmoil intensifies when Stella reveals identical genetics between mazoku and humans, shattering his core beliefs and pride.

Rejoining the conflict to aid the Zodiac X-Rares search, Barone receives the evolved spirit Lunatech-Strikewurm from a village elder. He confronts brainwashed allies like Duc, endures grave injuries, and uncovers mazoku leadership conspiracies. Post Queen Gilfam’s staged death, he allies temporarily with Dan before strategically defeating him to stabilize the mazoku capital. His final arc peaks in a decisive duel against Dan to determine the "trigger" for activating the X-Rares and halting Earth’s reset. Barone accepts potential sacrifice but loses; Dan fulfills the role heroically. In the aftermath, Barone delivers a unity speech to humans and mazoku, reconciling symbolically through a handshake with Clackey.

A decade later, Barone leads mazoku in a peace-seeking society. During an assassination attempt by anti-mazoku group Cardinal Sign, he battles Gratos for survival. Dan reappears unexpectedly, aiding Barone to secure victory. Barone then investigates Cardinal Sign and proposes a new world order where card battles replace weapons for resolving disputes, reinforcing his commitment to coexistence.

Later, after the Unified Government’s formation and emergence of the Mauve species, discriminatory policies force Barone and Clackey from power. Resenting oppression, Barone adopts a masked identity and establishes an independent sanctuary island as its anonymous ruler, "The Master," offering refuge to all races. He guides protagonist Gallet Revolt—a Core’s Light Bearer—to retrieve the hidden Mazoku Card. Barone challenges Gallet to a card battle, imparting philosophy on inherent traits and future-shaping power, now using an Armed Machines-centric deck instead of prior preferences. After aiding Gallet in deciphering the combined Human, Mazoku, and Mauve Cards, Barone watches the group depart unmasked from his balcony, reflecting on Dan’s legacy and seeing Gallet as a new world hope.

Barone’s distinct traits include green eyes, ponytailed blond hair, elf-like ears, white horns, and a tail. He typically wears purple attire with white accents. Across appearances, he wields a white deck featuring Brave spirits and moonlight-themed dragons like Strike-Siegwurm and Lunatech-Strikewurm. This motif defines his "Moonlight Barone" title and lunar associations, such as blessing Gallet under a full moon.