Chobe Aza, also known as the Bandit King, is a prominent criminal and survivor in the narrative who begins as a minor antagonist before eventually aligning with other main characters. He was born into a family of samurai vassals in the Iyo province, but his early life was marked by tragedy when his family fell from grace, his mother died of illness, and his father was executed. Left to fend for themselves, Chobe and his younger brother Toma were captured by thieves. Demonstrating his fierce will, Chobe took control of the group and established himself as the leader of a notorious band of outlaws. His criminal career earned him a death sentence, but his brother, having infiltrated the Yamada Asaemon executioner clan, secured Chobes release on the condition that he join an expedition to a mysterious island to find the Elixir of Life.

Chobe is a tall, lean, and muscular young man with unkempt blonde hair and a distinct braid on the right side of his head. His most prominent feature is a large scar covering the right side of his face, which resulted from him deliberately gouging out his own eye in the past to protect his brother from a threat. His attire is initially ragged, consisting of a torn coat over a red kimono, but he later acquires the clothing of the powerful beings known as Tensen and their Doshi servants.

His personality is defined by a brutal, barbaric, and ruthless nature, preferring to solve problems with immediate violence rather than words. He is sadistic in combat, often savoring the defeat of his enemies, and has no qualms about embracing the role of a villain. Despite this cruelty towards the outside world, his one absolute exception is his younger brother, Toma. Chobes primary motivation for surviving the island is to ensure Tomas safety, and he has proven willing to sacrifice everything for him. This bond is the core of his character. He is also highly intelligent and a remarkably rational thinker. He operates on a personal philosophy that those who adapt will survive, and he is capable of quickly evaluating a situation and setting aside his pride to form alliances or even cooperate with his enemies if it ensures his and his brothers survival.

Initially a wild card, Chobes role in the story is that of a powerful and unpredictable force. He and Toma operate as an independent unit, hostile to both the other criminals and the supernatural monsters on the island. After a crushing defeat by one of the Tensen named Jufa, Chobe makes the pragmatic decision to feign cooperation with the islands creators to buy time and reunite with his brother. Later, he forms a temporary but effective alliance with other major characters, including the samurai Gantetsusai and the Asaemon executioner Fuchi, utilizing his strategic mind to coordinate attacks against their divine enemies.

Unlike many other characters who undergo significant moral or emotional transformations, Chobe Aza remains remarkably consistent. His personal growth is not a change of heart but a mastery of his environment. His development is physical and tactical rather than philosophical; he adapts to the lethal rules of the island to continue doing exactly what he has always done: survive and protect his brother. Upon exposure to the islands mysterious energy known as Tao, Chobe awakens tremendous power. His most notable ability is the usage of Flower Tao, which grants him a terrifying form of regeneration, allowing him to heal from fatal wounds such as a broken neck or severed limbs almost instantly. He is also proficient with Metal Tao, using it to enhance his physical strength to superhuman levels, enabling him to wield heavy weapons and destroy massive stone constructs with ease. His physical resilience is immense, allowing him to withstand direct attacks from the Tensen. His cunning and high battle intelligence allow him to apply these abilities effectively, making him one of the most formidable combatants on the island.