Hyuse is a Neighbor from the militaristic planet Aftokrator who becomes a central figure after being stranded on Earth. He has short, messy light brown hair, pale skin, and blue or green eyes. Like all individuals from Aftokrator, he possesses two horns on his head that resemble a goat's, which grow from the back of his temples above his ears. After being left behind, he adopts Earth clothing, typically wearing a black hoodie to conceal his features. When operating as a Border agent, his Trion body is programmed to hide his horns, allowing him to blend in under the alias Hyuse Cronin.

Hyuse presents himself as a calm and collected individual who rarely loses his composure. Beneath this exterior lies a fierce sense of loyalty and deep respect for his superiors from Aftokrator, particularly Hairein and the elderly warrior Viza. He reacts with extreme anger when he perceives these figures are being disrespected or taunted. Hyuse is also highly competitive, once demanding a re-do during trainee exams specifically to beat another agent's record. He holds a deep, personal care for the head of House Ellin, a figure to whom he is closely connected, and experiences significant inner conflict over the possibility that his master might be sacrificed by Aftokrator.

Hyuse's primary motivation is entirely pragmatic. After being abandoned by his comrades during a battle in Mikado City, he agrees to join the Border defense organization solely as a means to secure a way back to his homeworld. He does not initially harbor loyalty to Earth or Border, viewing his enlistment as a transactional arrangement. His role in the story is that of a former enemy who becomes a temporary ally, bringing immense power and knowledge of the Neighborhood to the squad Tamakoma Second. He often serves as a rival and a measuring stick for other characters due to his exceptional combat prowess.

His key relationships are complex. Within Aftokrator, he holds great respect for the god-like leader Hairein and the legendary warrior Viza, who personally trained Hyuse in swordsmanship from the age of eight until he was fourteen. His relationship with fellow invader Enedra is strained and volatile, often leading to fights, though Hyuse reacts with visible shock and disbelief upon learning of Enedra's death. In the Tamakoma branch, he is initially mistrustful of the friendly branch chief Takumi Rindo and the tactician Yuichi Jin, though he shows a grudging respect for the latter. He develops a particularly annoyed dynamic with Kirie Konami, who reciprocates his dislike. He finds young Yotaro Rindo irritating at first, but later shows him gratitude, respectfully calling him his master or senpai. His relationship with his new teammates is one of growing professional cooperation, though his ultimate goal remains to return to his true lord.

Over the course of his integration into Border, Hyuse undergoes notable development. He transitions from a captive enemy to a grudging participant in rank wars, and finally to a more genuine, if still pragmatic, member of his new squad. During an interrogation at Border Headquarters, Hyuse angrily defends his loyalty to Aftokrator, stating that anyone going on an away mission must be prepared to die, demonstrating that his principles remain intact even in abandonment. He also shows a growing acceptance of his temporary allies, adapting to their strategies and even using his own privilege from a bet with Jin to demand he be taken back to Aftokrator, showing he trusts Jin to uphold his end of the bargain.

Hyuse is an exceptionally skilled and talented warrior whose abilities are recognized by both allies and enemies. His natural, above-average amount of Trion was further increased by the implantation of Trion receptors in his horns, which also enhanced the quality of his Trion and his proficiency at manipulation. He is an extremely fast learner. Within hours of enlisting in Border, he achieved B-rank status. He is an accomplished swordsman, having trained under Viza, and estimates his skill with a Kogetsu places him between the number four and number eight ranked Attackers in Border. He is also a highly capable Shooter, mastering the complex Viper trigger, and is one of only three agents who can create new bullet trajectories for it each time it is used. His strategic and analytical skills are formidable; he has memorized vast amounts of information about other units' triggers and strategies, and has demonstrated tactical acumen on par with his captain, Osamu Mikumo. Hyuse is also an extremely prolific user of the Escudo trigger, using his vast Trion reserves to create dozens of barriers in creative ways, such as propelling himself into the air, trapping opponents, or causing an Escudo to emerge directly from an enemy's body. His original trigger from Aftokrator is Lampyris, a powerful horn trigger that allows him to control magnetic projectiles to form shields, restrain enemies, and create a railgun.