Jinko Sumida presides over Seijumonji High School’s Discipline Committee as its iron-willed Chairman, her brown hair framing piercing purple eyes. Her uniform is marked by a green armband on her left arm, a bandage on her left cheek, long black socks, and polished brown shoes. A natural perfectionist, her stubborn and uncompromising demeanor leaves little room for leniency, enforcing order through the notorious "Ittokan tin can" method. Beyond her stern role, she harbors an unexpected passion for immersive gaming.

When tasked with directing a school play adaptation, Jinko’s relentless pursuit of flawlessness sparks clashes during rehearsals. Yet her meticulous focus gradually softens, allowing tentative bonds to form with the cast.

Jinko’s blood type is A.