Yuuki Kagurazaka, a Japanese otherworlder summoned to the Central World, began his life on Earth as a natural-born psychic genius raised by loving parents. Their deaths in a traffic accident caused by an overworked truck driver—and the subsequent court ruling that found the driver innocent—left him disillusioned with society's flaws. He initially contemplated revenge but shifted focus toward reforming the world through politics. Before enacting these plans, the former Demon Lord Kagali summoned him to another world intending to steal his body for reincarnation. During the summoning, Yuuki awakened his Unique Skill "Creator," developing "Anti-Skill" to resist Kagali's curse. He allowed Kagali to inhabit his body, promising to find her a new vessel and saving her life. Physically, Yuuki retains the appearance of a middle schooler despite his real age exceeding 40. He possesses black or light brown hair (sources vary), dark brown eyes, and a youthful, approachable demeanor—a consequence of his summoning and skill acquisition halting his aging. Personality-wise, Yuuki is driven by a core ideology of freedom and a desire to create a peaceful world for himself and his allies to live without constraints. He exhibits compassion, especially toward friends and victims of unjust systems, preferring negotiation over violence. However, his methods involve strategic ruthlessness and manipulation. Highly ambitious, patient, and resourceful, he masks his true intentions behind a cheerful, humble facade. He values loyalty within his inner circle, like the Moderate Harlequin Alliance, yet views others as tools. His traumatic past fuels his determination to reshape the world, leading him to blur moral boundaries. Yuuki's abilities center on his Unique Skill "Creator," enabling him to develop new skills. His signature "Anti-Skill" nullifies magic and abilities, including offensive and defensive effects. Though incapable of conventional magic, he can steal skills, such as Mariabell Rosso's "Greed," later evolving it into the Ultimate Skill "Mammon, King of Greed," which drains energy and manipulates memories through touch. His innate psychic talents and tactical genius further augment his capabilities. Key relationships define his influence. He trained under Shizue Izawa alongside Hinata Sakaguchi, leveraging this connection to reshape the Mutual Aid Guild into the Free Guild and becoming its Grandmaster. Under his leadership, the Guild implemented a monster-ranking system that reduced adventurer casualties and boosted trade. He revived Kagali as a loyal aide and co-founded the underground Cerberus to counter Mariabell Rosso. His interactions with Rimuru Tempest begin cordially; he facilitates Rimuru's role as a teacher for Shizue's students and bonds over shared Japanese culture like manga. Later, he orchestrates schemes against Rimuru through alliances with antagonistic forces, including Clayman and the Eastern Empire. Yuuki's story arc involves extensive political maneuvering. After 20 years building influence in the east, he moves westward, establishes the Free Guild, and secretly leads the Moderate Harlequin Alliance. He engineers conflicts, framing the Rosso family and manipulating Clayman to provoke Rimuru. During Tempest's founding festival, his machinations are exposed by Granbell Rosso, forcing him to flee. He allies with the Eastern Empire, rising to command its "Mixed Corps," but is controlled first by Emperor Rudra and later the angelic entity Michael. Yuuki feigns subservience to Michael, studies his powers, and eventually breaks free to rescue Kagali. His fate remains uncertain following a betrayal by Jahil during this rescue. A notable divergence exists between official media portrayals. The web novel depicts Yuuki as a primary antagonist motivated by boredom and power lust. The light novel (and its adaptations) reworks him into a morally ambiguous figure seeking world peace through chaotic means, with Mariabell Rosso and Feldway assuming the web novel's antagonist roles. This light novel iteration emphasizes his loyalty to allies and nuanced ideals. Trivia notes include his attachment to Japanese pop culture, particularly manga, which Rimuru replicates for him. His catchphrase references the Japanese TV show "Iitomo," and his leadership spans both the Free Guild and the Moderate Harlequin Alliance.