Yusa, a yuki-onna of the Ice Tribe, commands respect as a high-level demon while navigating dual loyalties between realms. Her protective instincts center on Kōji, her younger brother, whose bodily fluids yield strawberry and lemon-flavored syrups—a trait that draws her ire toward Jashin-chan’s persistent bullying. Childhood memories of resembling a diminutive mole provoke flustered retaliation when mentioned.

Wielding cryokinetic powers, she conjures indoor snowstorms, flash-freezes adversaries, and sustains entrepreneurial pursuits, though the demon world’s frigid climate stifles her cold-treat sales. This forces her to operate Eclipse, a human-world bar co-managed with Kōji, alongside ill-fated ventures like perilously discounted ice cream.

Resentful of narrative marginalization, she forges a Rebel Alliance with Mei Tachibana, plotting to dethrone the story’s central figures. Her poised demeanor fractures when overlooked, revealing jealousy or sharp-edged retorts. Interactions expose contradictions: icy vengeance against Kōji’s tormentors contrasts with warmth toward Yurine Hanazono’s kindness and Pekola’s emergencies.

Despite demonic prowess, commercial naivety undermines her ventures, while loyalty anchors her relationships. Collaborative ice attacks with Kōji in the "Waki Aiai Sabatsu Battle" game underscore their symbiotic bond. A shadowed familial tie to Charlie, her chocolate-factory-owning uncle, lingers unexplored as she straddles worlds, clashes with rivals, and chases acknowledgment amidst chaos.