Sōei began as a dark-skinned Ogre adorned with dark blue hair and a single white horn before Rimuru’s naming transformed him into a lean, humanoid Kijin exuding calm authority. As Minister of Intelligence and commander of the Kurayami, he orchestrates a sprawling espionage network rivaling powerful nations like Dwargon, mastering both subterfuge and counterintelligence. His disciplined professionalism masks a chūnibyō-infused passion for his ninja role, embraced with dramatic zeal that never hinders his efficiency. Fanatically loyal to Rimuru, he once nearly slaughtered a Lizardman for disrespect, yet his relationships reveal complexity: a rivalry-turned-partnership with Benimaru, wary evasion of Shion’s cooking disasters, and sly teasing of Souka, feigning obliviousness to her admiration.

During Rimuru’s Ingrassia expedition, a clone of Sōei partnered with Ranga, wryly mocking the wolf’s burgeoning popularity. He later subverted Glenda Attley’s assassination plot, sparing the cursed Otherworlder and recruiting her—a decision validated when Rimuru later lifted her affliction. Beyond duty, *The Slime Diaries* glimpses his softer affinity for cats, contrasting his shadowy vocation. His past as an Ogre survivor of the Orc invasion led him to Rimuru’s village, where Hakurou refined his stealth and tactical acumen. Now a strategic visionary, he collaborates with experts like Shuna and Diablo to counter magical threats. Though stoic, subtle wit emerges—mimicking Rimuru to provoke Shion or needling Ranga—hinting at a layered personality beneath his impassive mask.