Crocodine is a major character in the anime, initially serving as an antagonist before becoming a powerful ally. He is a humanoid reptilian beast with a towering, muscular build, a long strong tail, and pink scales covering his body that fade to a brownish tone on his underside. His appearance is further defined by his silver and black Roman-style armor, a white cape, and the loss of his left eye, a wound he receives during his first encounter with the heroes. As the former commander of the Furfang Legion, one of the six divisions of the Dark Army, he is known by the title Beast King and wields a signature weapon, the Vortex Axe, which is capable of generating vacuum-like slashes.

In his early appearances, Crocodine embodies the role of a fearsome and honorable warrior. He initially looks down on humans and despises those he considers weak, yet he operates under a strong, if misguided, personal code of honor. His primary motivation at first is to prove his strength and obey the orders of his superior, the dark lord Hadlar, who tasks him with eliminating the young hero Dai and his companions. This leads him to use underhanded tactics, such as kidnapping Dai's adoptive grandfather Brass to lure him into a trap, a scheme suggested by the cunning Zaboera. Despite his brutish demeanor, a sense of pride and the search for a worthy opponent drive his actions.

Crocodine's role in the story evolves dramatically after his defeat by Dai. Defeated but not destroyed, he transitions from a lethal enemy to a steadfast ally and key member of the main party. In this new role, he takes on the archetype of The Big Guy, acting as the physically strongest member of the group and a powerful frontline fighter. His key relationships transform with his allegiance; while formerly a subordinate of Hadlar, he becomes a devoted guardian to Dai, Popp, Maam, and the other heroes. He develops a particularly protective instinct toward the weaker members of the group, such as the small, timid monster Chiu, for whom he grows a notable soft spot.

Throughout the series, Crocodine undergoes significant character development. He sheds his initial prejudice against humans and his role as a mere brute, finding a new sense of purpose and honor in protecting his newfound comrades. His loyalty becomes absolute, leading him to perform multiple heroic sacrifices, repeatedly putting his own life on the line to ensure the safety of his friends without any hesitation. This protective nature solidifies his transformation from a simple beast king of the dark army into one of the most dependable and noble warriors among the heroes.

In combat, Crocodine relies on his immense physical strength, durability, and his proficiency with the Vortex Axe. Beyond his raw power, his notable abilities include a heat breath attack that can incinerate foes. He is also capable of unleashing a powerful, focused technique known as the Beast King Redemption Blast, which concentrates a tremendous amount of his power into a single, devastating strike that drastically swells the size of his arm and far exceeds his normal offensive capabilities.