Yuri Briar, Yor Forger's younger brother, is a recurring figure shaped by childhood tragedy. After their parents' deaths, Yor raised him alone, supporting them through undisclosed means. Her frequent returns home bloodied led Yuri to misinterpret her sacrifices as evidence of enduring hardship solely for his sake. This upbringing forged an extreme protective devotion towards his sister, dictating his life's trajectory. Academically gifted, he skipped grades to enter university at fourteen, later becoming a civil servant while secretly joining Ostania's feared State Security Service (SSS) as a Second Lieutenant. He conceals his SSS affiliation from Yor, believing she works at Berlint City Hall, just as he maintains a fabricated cover as a foreign ministry diplomat. Physically, Yuri shares Yor's black hair, pale skin, and striking red eyes, standing approximately 179 cm (5'10") and often noted as handsome. His SSS uniform consists of a green military suit, tie, peaked cap bearing the agency emblem, high boots, and black gloves. Off-duty, he favors a black business suit with a white shirt and blue tie, frequently topped with a light khaki trench coat, plus black gloves and shoes. Casual wear includes simpler items like jeans and shirts. Within the SSS, Yuri displays significant competence despite his youth. His duties encompass surveillance, interrogation, and identifying threats to national security, especially foreign spies. He harbors a specific vendetta against the Westalian master spy "Twilight," viewing him as an archenemy. His interrogation technique shifts from initial politeness to ruthless violence if cooperation falters. He exhibits sharp observational skills, deducing physical conditions and intentions from subtle cues, and maintains meticulous investigation logs. While proficient in marksmanship and combat, his abilities fall short against elite opponents. Crucially, he possesses extraordinary physical endurance—attributed to surviving Yor's unintentionally violent affection and consuming her toxic cooking throughout his life—granting heightened resilience to injury, poison, and illness. This endurance lets him fight through severe wounds, though he often disregards his limits, requiring intervention from others. Yuri's defining trait is an unhealthy obsession with Yor, termed a "sister complex." Stemming from her role as sole caregiver, it manifests as extreme protectiveness, jealousy towards anyone close to her, and an irrational belief in her infallibility. His patriotism and career are motivated by creating a safer country for her. This fixation impairs his judgment; he accepts Yor’s implausible explanations unquestioningly and prioritizes her approval above all else, including his own well-being. While genuinely loving her, his possessiveness breeds hypocrisy—he condemns dishonesty in others yet justifies his own deceptions as necessary for her protection. He displays occasional empathy, such as ensuring financial support for a suspect’s family, though these acts often align with his perception of Yor’s values. His relationships are heavily colored by this dynamic. He deeply distrusts and resents Yor’s husband, Loid Forger, mockingly calling him "Loi-Loi" or "Lottie" and subjecting him to hostile interrogations, suspecting him of harming Yor or being unworthy. Though unaware Loid is Twilight, Yuri shot him during an operation, fueling ongoing suspicion. Initially hostile toward Loid’s adopted daughter, Anya, due to her association with him, Yuri later assists her academically at Yor’s request, developing a begrudging neutrality. However, jealousy surfaces when Yor attends to Anya, and he once callously suggested her death during a crisis before recanting upon seeing Yor’s grief. Among colleagues, Dominic is noted as a rare friend, while a new SSS partner, Chloe, recently challenged his recklessness, forcing him to confront how his disregard for safety would distress Yor. Yuri's development shows early signs of change following failures and external critiques. After losing a confrontation with Twilight, he stewed in self-recrimination. Chloe’s intervention during a near-fatal incident marked the first narrative challenge to his single-mindedness, prompting him to acknowledge Yor would value his survival, suggesting potential future growth beyond his obsession. Key weaknesses include low alcohol tolerance, mirroring Yor’s; intoxication makes him impulsive and emotionally volatile, exemplified by erratic behavior like demanding Yor and Loid kiss before immediately regretting it. He also shares Yor’s lack of cooking skill, though his meals are merely unpalatable rather than poisonous.