Hartia is a young red-haired sorcerer from Tafurem who serves as a secondary character in the story. He is a former classmate and childhood friend of Orphen from their time as students at the Tower of Fang, the prestigious school for magic users. While the two were once very close, their paths diverged following a major incident involving another student, Azalie, leading Hartia to remain loyal to his master, Childman Powderfield, as Orphen broke away from the Tower.

By nature, Hartia is a caring and well-meaning individual who is deeply concerned for the welfare of those he considers friends, especially Orphen. He repeatedly tries to protect Orphen from what he believes are dangerous mistakes, even when it puts his own standing and safety at risk. Despite these good intentions, he has a somewhat submissive and less assertive personality compared to his peers, often ending up on the receiving end of pranks or physical comedy from his classmates. He also has a tendency to say things that are thoughtless or inconsiderate, and he becomes upset easily. A notable and defining quirk is his fondness for dramatic costumes and role-playing, primarily as his self-created alter ego, the Black Tiger, a masked superhero he emulates complete with a theatrical introduction.

His motivations are largely driven by a sense of loyalty and a desire to mediate between conflicting parties. He is caught in a difficult position, torn between his duty to the Tower of Fang and his master Childman, and his enduring friendship with the renegade Orphen. Rather than wanting to be an enemy, Hartia consistently attempts to warn Orphen away from danger and make him understand the truth behind the Tower's actions, hoping to reconcile the situation without violence. He risks his position as Childman's trusted apprentice, and even his life, to follow this path of a reluctant peacemaker.

His most significant relationship is with Orphen, whom he considers both a rival and a best friend. As students, Hartia was consistently the second-best student in their class, a position he found frustrating, as Orphen's natural talent often surpassed his own diligent practice. However, after Orphen left, Hartia’s own motivation and grades suffered, showing how integral their rivalry was to him. He holds a deep attachment to Orphen and is committed to saving him, even when their circumstances force them to fight each other. His other key relationship is with his master, Childman, who is the only person that truly trusts Hartia and chose him as an apprentice for his reliable and loyal nature.

Throughout the story, Hartia’s loyalty is tested as he uncovers the truth behind the Tower’s secrets, including the fate of Azalie and his master's true intentions. He has a notable moment of defiance when he disobeys Childman to confront Orphen under the guise of the Black Tiger, asking his master directly if he is truly willing to kill their former student. This inner conflict and his efforts to aid Orphen from within the system mark his development from a simple rule-follower to someone who acts on his own moral compass. His abilities as a sorcerer are considerable. While he may have less raw talent than Orphen, he compensates with rigorous practice, and in terms of pure magical power, he is considered to be on par with or even exceeding his friend. He suffers from a tendency to not perform well under pressure, which held his grades back at the Tower. His most distinctive ability is his transformation into the Black Tiger, which grants him the power of flight through silent magic and allows him to summon a bull wreathed in flames to fight alongside him.