Haia Salinvan Lyia serves as the third generation head of the Salinvan Guidance Mercenary Gang, a position he inherited following the death of his foster parent, Ryuhou. His upbringing involved rigorous training from a young age, making him a fellow disciple of the Psyharden sword technique, which creates a direct link between his skills and those of the protagonist, Layfon Alseif. He is recognized as a highly capable Military Artist, particularly skilled with a katana, and his abilities are sufficient to lead a notable mercenary group. He possesses a distinct appearance characterized by short, spiky orange hair, grey eyes, and a distinctive tattoo located over his left eye, which serves as a visible marker of his affiliation with the Salinvan organization.

The central driving force behind Haia's actions is his intense fixation on Layfon Alseif. He has harbored a long-standing interest in Layfon and is driven by a powerful desire to prove himself superior. This motivation is partly rooted in irritation, as he is bothered by the fact that Layfon, a fellow practitioner of their shared sword style, does not use a katana like himself. Haia's desire is complex; he wants both to defeat Layfon in battle and to fight alongside him at least once. He frequently taunts Layfon about being a former Heaven's Blade wielder, using this past status as a point of provocation. His fixation leads him to extreme measures, such as kidnapping Felli Loss to force a final, decisive duel with his rival.

In the narrative of Chrome Shelled Regios, Haia acts as a recurring rival and antagonist. He arrives in the Academic City of Zuellni with his mercenary gang, initially on a mission to retrieve a powerful entity known as the Haikizoku. The group later agrees to assist with the city's defense against contaminant beasts at the request of Karian Loss, though this does not diminish Haia's personal agenda. He engages Layfon in combat on multiple occasions. In their first encounter, he is overpowered and forced to retreat with help from his companion. During their second fight, he manages to scratch Layfon, a minor success, but ultimately loses his katana and suffers a wound. In his third and most desperate battle, which he forces by kidnapping Felli, he demonstrates his elemental ability of fire but is defeated decisively by Layfon. Despite his losses, his skill is evident, as he is shown to be capable of single-handedly defeating contaminant beasts while his gang members merely provide a distraction.

Haia's key relationships are largely defined by his rivalry with Layfon Alseif. He also has a close bond with his companion, Myunfa, who often supports him and helps him retreat from dangerous situations. Karian Loss, a key strategist in Zuellni, is aware of Haia's skills and arranges for the mercenary gang to assist the city, showing a transactional relationship based on mutual need. After his defeat, Haia leaves Zuellni but later returns at Karian's request, serving as his escort during travels to the city of Glendan.

Haia undergoes significant development in his professional pursuit of power. After his series of defeats, he competes in a formal contest to become a successor to a Heaven's Blade. He successfully wins this competition, earning the right to inherit the title of Heaven's Blade Wolfstein. Upon achieving this, he adopts a new name, becoming known as Haia Wolfstein Lyia, signifying his official acceptance as one of the most elite Military Artists in the world. His most notable abilities include mastery of the Psyharden sword technique, which he practices in the same lineage as Layfon, and proficiency with a katana, which he considers the proper weapon for their style. He can manipulate his internal energy or Kei, and during his final confrontation, he demonstrates the ability to use the element of fire in combat.