Chiaki Matsushita, a 17-year-old Taurus born April 25, attends Advanced Nurturing High School as a member of Class 1-D, reserved for students labeled academically or socially deficient. Though outwardly unremarkable, she deliberately masks elite academic and physical prowess to evade scrutiny, crafting a carefully curated persona to assimilate seamlessly. Officially graded B+ (76) academically, C (54) physically, and B (67) in social contribution, her true capabilities far exceed these scores—a tactical choice to preserve class equilibrium. Hailing from affluence, she exudes pride in her refined appearance and sharp intellect, discreetly assessing peers through lenses of aesthetics and competence. While forging surface-level friendships with classmates such as Kei Karuizawa, Maya Satō, and Satsuki Shinohara, her connections remain filtered through calculated analysis, prioritizing strategic utility over emotional attachment. Her singular ambition targets graduation from Class A to secure entry into a top-tier overseas university, followed by a career in global diplomacy. Her trajectory shifts upon uncovering Kiyotaka Ayanokōji’s latent genius during a year-end exam, prompting her to discreetly harness his skills for tactical gains. This alliance drives her to engage in mental math contests, endorse his leadership initiatives, and later support his controversial proposal to expel a classmate during a unanimous special exam—sacrificing individual bonds for collective victory. A survival test in her second year sees her proposing a partnership with him, swiftly rejected due to expulsion risks. Trust solidifies after a clandestine meeting where Kiyotaka tacitly confirms his suppressed talents. Their collaboration fractures when his third-year class transfer is announced, destabilizing her composure as she foresees diminished prospects for her class. Public exposure of their alliance heightens her unease toward looming challenges. Chiaki navigates conflicts with clinical pragmatism, sidelining sentiment for long-term gains. Moments of vulnerability—falling ill during a festival or reconciling friendships strained by secret leaks—surface briefly before she restores equilibrium. She operates under a meritocratic ethos, prioritizing outcomes over effort, yet sporadically indulges in cerebral challenges to stave off monotony. Romantic considerations remain confined to those mirroring her socioeconomic standing and intellectual acuity, reflecting an unyielding selectivity rooted in self-assured elitism.