Ririka Momobami, identical twin sister of Kirari Momobami and Vice President of Hyakkaou Private Academy’s Student Council, emerges from the shadows of a merciless familial tradition. Born into the powerful Momobami clan, her identity was erased after a ritual where newborn twins rolled dice to decide their fates. Kirari’s victory condemned Ririka to a life as her sister’s mirror, adopting Kirari’s appearance and stifling her own persona. A white theatrical mask with vocal distortion became her shield, hiding her face in public to preserve the illusion of a single entity. Though her features mirror Kirari’s—pale skin, platinum-gray hair, light blue eyes—Ririka distinguishes herself through loose hair and a lack of lipstick unless impersonating her sister. Silent and stoic, Ririka observes Student Council meetings as Kirari’s shadow, her loyalty unwavering. Without the mask, she unravels into shyness and social unease, a stark contrast to Kirari’s command. Years of conditioning to replicate Kirari’s every gesture enabled flawless impersonations, allowing the twins to swap roles and manipulate their clan’s power dynamics. The presidential election arc fractures her facade. Mary Saotome’s bold removal of Ririka’s mask during a gamble involving poisoned chips forces her timid self into the open. Mary’s influence sparks gradual transformation: Ririka discards the mask, confronts rivals like Rin Obami and Nozomi Komabami independently, and unveils strategic prowess—exposing Rin’s deceit and empathizing with Nozomi’s plight. In *Kakegurui (Kakkokari)*, her masked persona takes a comedic turn, the mask twisting to display exaggerated emotions like blushes or sweat. She communicates through notes and gestures, often muddling interactions. Yet her devotion to Kirari persists, even as others confuse her identity, such as when Mary wears her spare mask. Ririka’s defiance peaks in a direct gamble against Kirari. Though defeated, Kirari’s recognition of their separate identities—affectionately calling her “big sis”—marks Ririka’s emergence from suppression. Later actions, like intervening in Yumeko Jabami’s gamble via a decisive coin flip, cement her agency. Her journey weaves themes of identity and liberation against familial control. The twins’ bond, tangled in manipulation, reveals flickers of mutual care—Kirari engineers the election to free Ririka. The duality of masked authority and unmasked fragility underscores her character, mirroring the series’ exploration of illusion versus truth.