Bound to vampire Alucard von Mosquiton through supernatural ties, Yuki serves as one of his familiars. She acts as an ice guardian, contrasting her counterpart Hono's fire-based abilities. Her primary role involves protecting Mosquiton and supporting his human contractor, Inaho Hitomebore, during their quest to locate the O-Part artifact.

Yuki typically manifests as a young girl, a form restricting her full powers. To unleash her complete capabilities, she transforms into an adult woman. This matured state allows her to engage effectively in combat alongside Mosquiton and allies against supernatural adversaries threatening their mission.

Her abilities center on ice manipulation, offering tactical advantages in battles fought across global locations. Shifting between her two forms remains a consistent aspect throughout her appearances. Yuki's actions and combat contributions directly support Mosquiton and Inaho's central objective.