Shirayukihime, a princess by birth from the magical world of Phandavale, serves as one of the Three Musketeers protecting Souta Suzukaze and the Erde Key he possesses. Her kingdom faced usurpation after her father remarried a woman controlled by the antagonist Cendrillon. As a top magic student, she wields intellectual ice and water-based attacks, contrasting her fellow Musketeers' physical or earth-based abilities.

She openly harbors feelings for Souta, frequently initiating physical affection like hugs. This creates tension with his childhood friend, Ringo Kinoshita, fueling interpersonal conflicts within their group. Her potent magic occasionally escapes control during sleep, forcing her to remain awake at night to prevent dangerous consequences for others.

When separated from her companions, Shirayukihime joins forces with Akazukin and Ibarahime to activate "Princess Mode," an enhanced magical state boosting her combat power. Her royal lineage and academic excellence establish her as a key strategist against Cendrillon's forces during missions traversing both Phandavale and Erde.