Azudora, also known by the epithet Blue, is one of the Four Heavenly Kings of the Demon World. He possesses a humanoid form characterized by long, pointed ears and flowing light blue hair, with blue eyes to match. His calm and levelheaded demeanor stands in stark contrast to that of his fellow Heavenly King, Vamirio. Despite his composed nature, he harbors a playful side and greatly enjoys teasing Vamirio. This includes playing pranks on her, such as tricking her into eating bad-tasting candy just to see her disgusted expression, and deliberately addressing her with a familiar honorific that he knows she dislikes. Beneath these antics, Azudora is deeply protective of Vamirio, consistently prioritizing her personal safety.

In his distant past, Azudora was a merciless and terrifying figure on the battlefield during the ancient wars between humans and demons. As one of the Four Heavenly Kings even then, he wielded a powerful demon sword and cut down countless human warriors. His perspective was fundamentally changed when he met a human hero named Uria. Despite initial caution, the two became very close friends. Through Uria, Azudora came to know the human race more intimately, even visiting his friend's village. This experience made him abandon his desire for conflict, and together, he and Uria worked toward the possibility of peace. However, the war only worsened. The humans, cornered, resorted to a forbidden apocalyptic magic that nearly ended the world. Uria was transformed by this power, and Azudora was ultimately forced to kill his own friend to save the world. This tragic event cemented his belief that peace is possible and shaped his actions for centuries to come. In a later era, he found a young Vamirio and took on the role of raising and preparing her to become a Heavenly King.

Within the story, Azudora is a figure of immense authority and strategic importance. After the previous Demon King is killed, he is responsible for organizing the next tournament to select a successor. He is a proponent of coexistence with humanity, and upon meeting the human hero Helck, he makes it clear that the Demon Empire has no desire to attack humans unprovoked. He is a pragmatic leader who prefers to avoid violence when possible but will not hesitate to fight when necessary. He also serves as a crucial source of wisdom and magical knowledge, often explaining complex magical phenomena to others.

Azudora shares a key relationship with Vamirio, acting as her guardian, mentor, and colleague. He is highly protective of her, though he also enjoys provoking her with his teasing. His past friendship with the human hero Uria is the most defining relationship of his life, as it directly led to his change in ideology and continues to haunt him. His interactions with Helck are initially cautious, but he comes to see the human hero as an ally. He also has a history as an adversary to other powerful figures like Mikaros and Edil, the latter of whom manages to critically wound him during the human assault on the demon castle.

Azudora undergoes significant development from his early days as a ruthless warrior to a calm, diplomatic leader who actively seeks to save humans rather than destroy them. The trauma of losing Uria drives his determination to find a better way. Even after being severely injured by Edil and left for dead, he survives and continues to strategize and fight for a future where humans and demons can coexist. His resolve is encapsulated in a vow to save Uria's people.

As a fighter, Azudora is exceptionally powerful. Despite his own claims of being the weakest of the Four Heavenly Kings, others believe he is the strongest under the right conditions, specifically in environments rich with plant life. His primary form of magic is Wood Magic, which allows him to control all of the Empire's trees, manipulating and shaping them to his will even if they are damaged, as long as their roots survive. He can create and fire powerful magical lances of wood, among other abilities. He is also skilled in Searching Magic to locate individuals or objects. In the past, he was a master swordsman who used a cursed heirloom blade known as the Hero Killer, a weapon especially powerful against humans. As a sign of his resolve to abandon his violent past and seek peace, he cast this sword aside. He also possesses immense speed, capable of subduing an army of a thousand soldiers in an instant, and incredible survivability, having endured seemingly fatal injuries on multiple occasions. He is also a skilled magic researcher, having created the magical contracts and rings used during the Demon King tournament to prevent participants from harming civilians or each other.