Yū Asuka (飛鳥 優) is a teenage girl with brown twin-tail hair, V-shaped bangs, and striking blue eyes. Her slim 160 cm frame, pale complexion, and proportions of 91-55-90 cm are accentuated by a wardrobe blending lolita fashion with delicate ribbons, cuffs, and hair accessories. Driven by loyalty to her café-managing brother-in-law Masaki—whom she calls “brother” despite no blood relation—she enters a martial arts tournament to settle his debts, prioritizing his security over her own safety. Her selflessness clashes with a fiercely competitive streak, as she battles opponents despite risks of humiliation or harm.

This resolve falters when forced to defeat a close friend early in the competition, leaving her guilt-ridden yet compelled to continue. Unarmed combat skills propel her through matches, though her training origins remain undefined. Interactions with Masaki and legacy figure Yuka underscore her struggle to reconcile empathy with obligation, her growth defined by resilience amid ethical clashes. The tournament tests her limits, framing her journey through immediate challenges rather than extended character arcs.