Kirari Momobami reigns as Hyakkaou Private Academy’s student council president and heiress to the powerful Momobami clan. Chosen as the clan successor at birth through a dice game that condemned her twin sister Ririka to a life behind masks, her formative years forged a worldview where life unfolds as a sequence of high-stakes gambles, with dominance and strategy dictating victory. She seized control of Hyakkaou two years before the main narrative by toppling the former president in a gamble, then restructuring the academy into a meritocracy where gambling skill and financial clout define social rank. This hierarchy included the dehumanizing "housepet" tier—students burdened by debt, stripped of autonomy, and bound to life plans meticulously drafted by the council. These plans dictated careers, marriages, and personal choices long after graduation, cementing Kirari’s influence over their futures. Her demeanor merges icy precision with a detached, experimental curiosity. She frames the academy as her personal aquarium, its students reduced to specimens in her ongoing study of human behavior under duress. Beneath a veneer of elegance lies a penchant for cruelty: she coolly proposed purchasing Midari Ikishima’s eye post-gamble and watched impassively as housepets endured public degradation. Yet glimpses of vulnerability surface in select relationships. She shares an unguarded bond with Ririka, openly nurturing her sister’s independence. With secretary Sayaka Igarashi, she intertwines calculated tests—like a staged suicide plunge to gauge loyalty—with genuine protectiveness, ensuring no true harm befell her. A defining shift occurs when she dismantles the student council, sparking a presidential election open to challenges from both the Momobami family and student body. This move aims to shatter complacent power structures and ignite chaos, feeding her appetite for observing unpredictability. Her rivalry with Yumeko Jabami, a fellow gambling prodigy, underscores their divergent drives: Yumeko chases adrenaline, while Kirari savors the act of dismantling order to reaffirm control. Throughout her schemes, she operates by a creed where authority and inquisitive ambition eclipse ethical boundaries. Systems like the housepet classification crumble once they bore her, replaced by fresh experiments to test societal hierarchies. As both clan leader and academy architect, her life’s work revolves in perpetual motion—crafting and unraveling power dynamics through meticulous risk and manipulation.