Yutori Kokorogi, a classmate of Yuuichi Katagiri and participant in the Adult Tomodachi Games, presents a fragile exterior of quiet shyness and gentle kindness, shaped by years of bullying in middle school and high school until Shiho Sawaragi’s intervention integrated her into Yuuichi’s circle. Outwardly innocent and gullible, she channels genuine enthusiasm for anime and manga into creative hobbies, masking a cunning, obsessive psyche fixated on Yuuichi—a fixation rooted in a cryptic encounter predating their high school years. Her past reveals survival forged through exploitation: during middle school, she traded suggestive photos for financial support from older men, drawing a firm line at physical escalation. This history of transactional relationships and relentless bullying bred a deep distrust of others, fueling her mastery of deception. Though projecting an image of poverty, she hoards secret wealth and exhibits violent impulses, exemplified by tasing her mother. Her duplicity peaks when she frames Shiho for murder, manipulating the group’s forced entry into the Tomodachi Game. Operating as the group’s traitor, Yutori deploys calculated charm, strategic affection, and meticulous schemes to steer game outcomes. Her obsession with Yuuichi drives extremes—bankrolling elaborate plots and attempting murder—all to monopolize his attention, though her loyalty remains a self-serving illusion. She thrives as a paradox: a devoted friend masking a ruthless strategist who sacrifices alliances for personal ambitions. Her prolonged success in deceiving Yuuichi and peers underscores her adeptness at social manipulation and performance. Alliances with shadowy figures from Yuuichi’s past intensify her disruptive role, entangling the group in external vendettas. Yet her singular focus on Yuuichi emerges as a tactical weakness, skewing her decisions. The exposure of her betrayal fractures group trust, devastating Shiho, who becomes collateral in Yutori’s machinations. Her narrative arc dissects duality, trauma, and manipulation, casting her as a pivotal antagonist who tests the group’s unity and ethical boundaries. Through her, the story interrogates the psychological intricacies of trust and betrayal within perilous, high-stakes arenas.