Yuni captains a unit within the Sorcerer's Army, part of the Volunteer Army resisting the Black Army's conquest. She possesses lilac or pink hair in pigtails and striking red eyes, wielding an oversized weapon merging sword and magical focus.

Stoic and emotionally restrained, she maintains intense focus during missions, rarely revealing her feelings. This control underpins her reputation as a rational, effective soldier. Yet profound loyalty defines her core; she willingly faces great peril to protect allies. Her personality blends caution, skepticism towards the unfamiliar, and reliance on protocols with a deep need for security and guidance.

As a Rune Fencer, she seamlessly combines swordsmanship with potent magic. Her specific affinity is ice manipulation, earning her the moniker "Goddess of Ice" for her power to control and unleash freezing forces. She engages foes at melee or range, piercing adversaries from afar with magical strikes or instantly freezing them with her blade. Her tactics include defense-ignoring effects and enhancing allied combat capabilities.

Within the Volunteer Army's campaigns, she serves as crucial support for the protagonist Aram, aiding his development and confronting his past while fighting in pivotal battles against the Black Army. Both allies and adversaries recognize her strategic importance.

Beyond the main series, she appears in crossovers like Brave Frontier as a summonable unit. There, her abilities center on powerful water-based area attacks, defense-ignoring effects, and boosting allied offensive power, consistent with her ice affinity and leadership role.