Hiiro, an ogre and former member of the Ogre Village destroyed by orcs, survived the massacre only to become a mercenary under Demon Lord Clayman alongside fellow survivors. Deserting Clayman's army led to a severe injury inflicted by Clayman's soldier Yamza during an attack. Found by the people of the Kingdom of Raja, he recovered under their care and received his name "Hiiro" from Queen Towa. Ten days later, he escaped Raja, returning to his village solely to confirm its destruction. Driven by vengeance against the orcs, he returned to Raja four days later and swore loyalty to Towa. Sent as Raja's messenger to the Jura Tempest Federation to request permission for cultivating part of the Great Jura Forest for food, Hiiro attacked Geld and the orcs, consumed by his desire for revenge. Geld, recognizing Hiiro's motive, dropped his weapons to accept death. Benimaru intervened, pacifying Hiiro. This confrontation reunited Hiiro with his childhood friends and fellow ogre survivors: Benimaru, Shion, Shuna, Hakuro, Souei, and Kurobe. Learning the orcs had been manipulated by now-defeated forces and were no longer enemies, Hiiro reconciled with Geld. Back in Raja, Hiiro discovered Towa suffered from Curse Poison, caused by using her tiara's power to purify a toxin-filled lake. He later learned the lake was poisoned by Lacua, a merchant scheming to gain favor with the Primordial Demon Violet. Lacua tricked Hiiro into ingesting a Curse Orb, falsely claiming it could transfer Towa's soul to his body. Fed manipulated memories of his village's destruction, Hiiro transformed under the orb's influence. Benimaru fought to halt his rampage while Rimuru pursued Lacua. Hiiro ultimately removed and destroyed the orb himself. To save him from its effects, Towa used her tiara's full power, sacrificing her life until Violet voided their contract and revived her as an apology for Lacua's actions. As the strongest warrior from his ogre village, Hiiro possesses exceptional sword skills. His unique skill, "Berserk," enables him to momentarily overwhelm formidable opponents like Yamza. He employs combat arts such as "Instantmove" for high-speed movement and "Flowing Water Slash" for precise attacks. His fire-affinity abilities include "Fire," "Fireball," and "Flame Sword," alongside mystic arts like "Ogre Flame." He wields a custom nagamaki sword forged by Kurobe as a reward for his bravery and wears a distinctive robe. Hiiro evolves from a vengeful survivor to a protector of Raja, demonstrating unwavering loyalty to Towa and achieving reconciliation with his past. His combat prowess and fire-based abilities remain central to his role.