Benimaru began as the unnamed prince and heir of the ogre tribe. After the Orc Lord's army destroyed his village, he fled into Jura Forest with his younger sister Shuna and survivors Shion, Souei, Hakurou, and Kurobee. Mistaking Rimuru Tempest for the masked attacker Laplace due to his appearance, Benimaru led an assault but was swiftly overpowered. Upon realizing their error and hearing Rimuru's explanation, Benimaru apologized, accepted refuge, and formed a temporary mercenary alliance. Rimuru later named him Benimaru ("Crimson Circle"), evolving him and his companions from ogres into kijin. Following the defeat of the orc army, Benimaru pledged permanent loyalty to Rimuru. Originally an ogre, Benimaru stood roughly 200 cm tall with a bulky build, reddish skin, long crimson hair, prominent black horns, sharp orange-red eyes, visible fangs, and distinctive red tear-like markings beneath his eyes—scars from a childhood accident involving Shuna. He wore maroon samurai armor over black clothing featuring a white fur collar. His kijin evolution reduced his height to 180 cm, normalized his skin tone, slimmed his horns, and straightened his hair. His attire changed to a brown kimono with white fur linings, later upgraded to a red, yellow, and white kimono matching his hair and eyes. He wields the katana "Guren," forged by Kurobee and strengthened into a mythical-grade weapon. Benimaru displays a carefree, confident, and battle-enthusiastic personality tempered by fundamental caution and cunning. Initially hot-headed, he grew more rational and calm after becoming Rimuru's military commander. He values strength and loyalty, refusing to serve those he deems unworthy but never belittling the weak. He possesses a strong sense of justice and responsibility, though he initially hesitated to lead his tribe. Serving Rimuru allows him to pursue battle without administrative burdens. He is fiercely protective of allies, especially Shuna, but exhibits awkwardness in romance, eventually marrying both Momiji (a tengu) and Albis (a beastkin). He dislikes carrots but enjoys sweets. He holds key positions: Minister of Defense for the Jura-Tempest Federation, Commander-in-Chief during wartime, leader of the "Big Four," and a top-tier member of the Twelve Guardian Lords. He ranks among Rimuru's three strongest subordinates alongside Diablo and Zegion. His combat prowess blends masterful swordsmanship trained by Hakurou with innate fire manipulation, enhanced by naming and evolutions. Key powers include: - **Unique Skill "Grand Marshal":** Enhancing battlefield awareness, spatial perception, and strategic command. - **Ultimate Skill "Lord of Sunlight (Amaterasu)":** Granting control over fire, light, space, and time; thought acceleration; and absolute sensory perception. - **Signature Techniques:** "Hell Flare" (black flames negating regeneration), "Oboro Black Flame: Hundred Flowers" (high-speed slashes), and "Prominence Acceleration" (dragon-shaped energy wave). - **Team Attacks:** "Quartet Skill: Breakdown Nostalgia" (with Diablo, Zegion, and Dino). - **Resistances:** Immunity to physical, natural, and magical attacks; high resistance to mental, holy, and elemental effects; and protection against soul, existence erasure, and spatial manipulation as a Flame Spirit Oni—a spiritual lifeform regenerating as long as his core remains intact. His relationships center on unwavering loyalty to Rimuru, whom he trusts implicitly. He shares a deep bond with Shuna, relying on her for domestic matters. Among his ogre companions, Souei is a close confidant, Hakurou a respected mentor, and Shion a fellow warrior despite her clumsiness. He maintains a respectful rivalry with Diablo. His marriages to Momiji and Albis produced children, though both wives subtly compete for Rimuru's favor. He also shares a vegetable-averse camaraderie with Milim Nava. Post-evolution, Benimaru led armies in major conflicts like defending Eurazania against Clayman's forces, mastering techniques through observation and training. He swore a personal oath with Rimuru using the phrase “Shion’s cooking is really bad” as a contingency test for Rimuru's mental state. Despite his status, he remains approachable, undertaking tasks like fire prevention campaigns or snow removal using his abilities.