Benimaru

Originally the son of the chief who ruled the village of the Ogre tribe, and the brother of Shuna. In Volume 2 of the books, he becomes a subordinate of Rimuru, evolves into an Oni tribe through Rimuru's naming, and becomes a handsome man about 180 cm tall with jet-black twin horns, crimson hair, and eyes. Through Rimuru's evolution into a Demon Lord species, he becomes a Specter, and after being given a soul by Rimuru in Volume 14, his lingering regrets as the clan leader are cleared, awakening and evolving into the Flame Spirit Oni, and he is appointed as one of the Holy Demon Twelve Guardian Kings with the title of Flare Lord.

He has a combative and somewhat short-tempered nature, but he has more self-control compared to his brethren. He is highly trusted by Rimuru and serves as the general who has command over all the armies. He becomes the commander of the Crimson Flames (Kurenai), formed from the former Child Oni tribe named by Rimuru, and the Green Numbers. After the military reorganization following the founding of the Jura Tempest Federation, he hands over the command of the First Corps, including the Green Numbers, to Gobta, and instead serves concurrently as the general of the Fourth Corps, formed from the Red Numbers. Due to his pure-hearted nature, he was not very enthusiastic about marriage, but recognizing the passion and resolve of Momiji and Albis, he marries both and has children who become the successors of the clan.

In battle, he becomes one of the three apexes under Rimuru, characterized by his swordsmanship combining flames and his katana, using Hell Flare, which incinerates confined spaces with extreme heat. Through rigorous training, he surpasses his masters Hakurou and Albert to become a swordsman who can unleash the swift sword flash of Oborokuroen Hyakkaryouran. He possesses the unique skill "Grand Marshal (Svermorno)," which allows him to have excellent spatial recognition and accurately predict outcomes, and after awakening, he acquires the ultimate ability "King of Mirage (Amaterasu)," which controls and accelerates light and heat based on the authority of Velgrind.