Hakurō began as an unnamed ogre serving as the martial instructor and strongest swordsman in the Ogre Tribe’s royal guard. Grandson of master swordsman Byakuya Araki, he notably trained Gazel Dwargo 300 years before the main timeline. Defying typical ogre lifespans of 100 years, he lived over 300 years until encountering Rimuru Tempest. After his village’s destruction led to a confrontation with Rimuru, the conflict resolved with Hakurō swearing allegiance upon receiving his name. This naming evolved him from an ogre to a Kijin, rejuvenating his appearance and extending his lifespan. He later evolved into an Oni after Rimuru’s ascension to Demon Lord, though this caused no significant visual changes beyond his Kijin form. Initially appearing as a short elderly ogre with aged silver hair, ivory-like horns, pointed ears, and black eye lines, he contrasted sharply with typical ogre physiques. His layered robes included a pale brown scarf covering his mouth and fingerless gloves. As a Kijin, he transformed into a middle-aged prime with sharper hair, a silver goatee, and defined facial features. His skin lost its subtle silver tint, and his horns shrank. He typically wore a white overcoat, occasionally with a scarf in adaptations. Hakurō remains calm and analytical, especially in combat, where he identifies opponents’ techniques after a single use. He despises being called "old man" and threatens violators with intensified training or death. A strict instructor, he emphasizes martial arts and swordsmanship over innate skills, criticizing monsters’ overreliance on abilities. He dotes excessively on his daughter Momiji, pressuring Benimaru to marry her and showing visible annoyance at Benimaru’s hesitation. His legendary combat prowess prioritizes skill over raw magicule capacity. Ranked Disaster-class by human systems, his sword mastery lets him challenge higher-tier foes. Key skills include "Martial Master" (incorporating "Heavenly Eye," "Thought Acceleration," "Ultra Acceleration," "Foresight," and "Mystery"), "Magic Power Perception," "Multilayer Barrier," "Steel Strength," and resistances like "Abnormal Condition Nullification." His signature "Hazy Style Sword Arts" feature techniques such as "Flowing Water Slash," "Thunder of Heaven and Earth," and "Double Cherry Blossoms - Eight Petals Flash." He wields "Samegumo," a Legend-grade cane-shaped katana forged by Kurobe. As Chief Instructor of Tempest’s military and an executive, he rigorously trains warriors including Rimuru, Gobta, and the Goblin Riders. He mentored Benimaru in swordsmanship since childhood, affectionately calling him "Young Master" even after joining Rimuru. He shares a long history with Shion, having trained her since youth while avoiding her cooking. With Gobta, he identifies latent talent and mentors him, forming a familial bond despite exasperation at Gobta’s laziness. His familial ties to Benimaru solidify after Benimaru marries Momiji. In the movie "Scarlet Bond," Hakurō reunites with Hiiro, another ogre survivor, after Hiiro attacks Geld and the orcs. He aids Rimuru in Raja, combating the curse poisoning Queen Towa and confronting external threats, reinforcing his role as a steadfast ally.