Keyarga, originally named Keyaru, began as a kind-hearted youth from Alban Village chosen as the Healing Hero. He dreamed of saving the world but feared his healing magic forced him to absorb patients' memories and pain. Villagers described his initial personality as indecisive, kind, and optimistic, driven by a desire to prevent children from experiencing the loneliness he endured after losing his parents.

During his first timeline, Keyaru suffered four years of systematic torture, drugging, physical abuse, and repeated rape by Princess Flare Arlgrande Jioral, fellow heroes Blade and Bullet, and Jioral Kingdom soldiers. They exploited his healing abilities to bypass their level caps, addicting him to opioids for control. This trauma, compounded by his village's destruction and the suicide of his first love Anna (triggered by her rape by Knight Captain Renard using Keyaru's face), eradicated his former kindness. He developed extreme misanthropy, viewing humanity as inherently corrupt, and focused solely on vengeance.

After defeating the Demon King Eve Reese, Keyaru used the Philosopher's Stone to rewind time four years, retaining his memories. Adopting the alias "Keyarga," he deliberately cultivated drug resistance preemptively and executed calculated revenge: He tortured and raped Flare, erased her memories, and transformed her into the submissive "Freia." He transformed Renard into a woman, orchestrated his gang rape by brainwashed soldiers, and burned him alive. Using the female persona "Keara," he lured Blade into a trap where she was raped and devoured by drugged assailants. He captured, raped, and memory-wiped Princess Norn (Flare's sister) into "Ellen" after she ordered executions including his friend Karman.

Keyarga's healing magic granted versatile abilities: Recovery Heal restored beings to optimal condition while forcing him to endure the target's lifetime pain; Imitation Heal copied abilities from healed targets; Looting Heal stole experience points and mana; Corruption Heal inversely manipulated biology for instant kills; Transformation Heal altered appearances, genders, memories (blocking recall, not creating new ones), and talent stat distributions. He used Transformation Heal for disguises like Keyaruga (older male form) and Keara (female form). Supplementary skills included poison/drug immunity, pain resistance, combat precognition via "All-Seeing Eye," alchemy for aphrodisiacs/toxins, and stat optimization.

Post-betrayal, Keyarga exhibited sadistic, manipulative, and vengeful traits, finding pleasure in inflicting suffering. He adhered to a personal code against harming innocents and aided others seeking justified revenge, such as demi-humans. He referred to his female companions Freia, Setsuna, Ellen, Eve, and Kureha as "toys," viewing them initially as tools. However, he displayed protectiveness when they were threatened and acknowledged moments where his "thirst for revenge vanished" during travels with them. Some narratives suggest unconscious attachment, though he suppressed this out of fear of loss.

After eliminating Bullet the Gun Hero and dismantling the Grantsbach Empire, Keyarga achieved his vengeance. He usurped the Jioral throne, intending to rebuild the kingdom into a peaceful nation. His long-term goals shifted toward protecting his companions and maintaining hard-won stability.