Mikura Sado serves as a supporting character, first appearing as the devoted housepet of Sachiko Juraku, Hyakkaou Private Academy’s Public Morals Committee Chairwoman. Her shoulder-length red hair is tied into twin pigtails, framing dark blue eyes noted for their hollow gaze. She dons the standard uniform with black thigh-high stockings and brown loafers, accessorized by a housepet badge and a collar fastened with a chain—visible in daily settings but concealed beneath formal attire during special events. Once a merciless sadist, Mikura reveled in crushing opponents through high-stakes gambles, relishing their humiliation and financial collapse. This ended when Sachiko defeated her, imposing a life of servitude. Publicly shamed and collared, Mikura repeatedly gambled to reclaim freedom, each loss eroding her defiance until she embraced subservience. She later confessed her past cruelty lacked true satisfaction, finding purpose instead in Sachiko’s control and her own masochistic surrender. Fiercely loyal, Mikura obsessively seeks Sachiko’s approval, demanding punishment for any perceived shortcomings. Her jealousy erupts when Mary Saotome threatens her position, prompting Mikura to sabotage Mary during a gamble—a scheme exposed and punished by Sachiko. Yet during the Hidden Rule Game, Mikura allies with Mary, unearthing remnants of her former resolve while aiding Mary’s escape from a mirrored downfall. This fragile partnership sparks self-reflection, blending residual defiance with reluctant growth. Mikura’s surname—combining “help” (佐) and “handing over” (渡)—hints at her duality, echoing themes of sadomasochism. Unique in the series, she plays mahjong and bears a hiragana-written first name. Her arc traces a psychological metamorphosis, navigating power shifts through relationships with Sachiko and Mary, embodying the tension between dominance and submission.