Bel emerges as a cunning antagonist within the Mercenare Trio, ascending to leadership through ruthless ambition. Sporting a bearded visage, sunglasses, and a black coat edged in green, his purified form reveals a rodent-like body with grey fur and bat-like wings. He embodies the sin of sloth, channeling the demonic influence of Belphegor through lethargy, sadistic manipulation, and a penchant for delegating dirty work to subordinates Ira and Marmo—enforcing their obedience via Blood Rings crafted from stolen Janergy.

Strategically methodical, Bel consolidates power by draining rivals Leva and Gula of their energies. He weaves psychological warfare, kidnapping Ai—a vital source of Loveads—to destabilize enemies and deploying traps that exploit emotional weaknesses, endangering Cure Heart through calculated hostage scenarios. His arsenal includes mirrorless teleportation, a Beast Mode transformation into a Jikochuu Cellphone, and a fleeting fusion with Proto Mercenare after absorbing remnants of King Jikochuu’s energy, unleashing cataclysmic power.

Bel’s ambitions evolve from usurping the Trio to pursuing godlike dominion, marked by schemes like imprisoning Princess Marie Ange and corrupting Trump Kingdom. Repeated clashes with protagonists shatter his fused form, reducing him to a powerless mouse. He views Regina with scorn for her immaturity and authority, while former allies face betrayal without remorse. His arc closes as he slinks into obscurity alongside ex-subordinates, his legacy etched by treachery and the corrosive apathy of sloth.