Hayase Yuuka oversees club budgets as treasurer of Millennium Academy’s Seminar council, enforcing strict financial accountability with mathematical precision. Her abacus serves as both tool and anchor, steadying her focus during high-stakes calculations and tempering frustrations sparked by colleagues’ carelessness. Though professionalism defines her demeanor, impulsive peers often provoke sharp reprimands that mask her genuine commitment to organizational efficiency. Meticulous in her duties, she discreetly alters receipts to hide personal oversights, prioritizing an image of infallibility over transparency.

Structured environments bring out her composed courtesy, but unpredictability tests her patience—evident in her rejection of chance-based games like poker. Her dynamic with Sensei balances vexation at their spending tendencies against growing respect for their dedication to students, fostering unspoken fondness beneath surface-level exasperation.

Navy blue pigtails secured by triangular accessories frame bright blue eyes pierced with red slit pupils, crowned by a halo resembling a black ring bisected by a azure stripe. She pairs Millennium’s standard uniform—hoodie, blazer, white shirt, and blue tie—with a bullet-pouched belt accentuating her black skirt. Twin SIG MPX submachine guns bearing the academy’s emblem underscore her combat readiness.

In battle, she prioritizes tactical resilience, erecting barriers scaled to healing output and fortifying allies through methodical passive boosts. A scientific calculator remains at her side, a tangible emblem of her quest for flawlessness despite her innate mental arithmetic skills. Her interactions oscillate between rigid discipline and the chaos of collaborative environments, painting a portrait of intellect strained by responsibility yet softened by evolving bonds.