Kyoko is the elder sister of Shoko and the original bearer of the Equuleus Bronze Cloth, serving as one of the Saintia, the personal guard of the goddess Athena. She spent years away from home training to become a warrior, leaving her sister behind with a promise to protect her. Kyoko possesses a calm, composed personality and a natural inclination for leadership, and her defining trait is a deep, self-sacrificing devotion to her younger sister.

When the goddess of discord Eris sought to take Shoko as her vessel, Kyoko intercepted the attack and willingly surrendered her own body, allowing Eris to possess her so that Shoko would be spared. This act of sacrifice sets the entire story into motion, as Shoko inherits the Equuleus Cloth and becomes a Saintia with the sole aim of saving her sister. As a Saintia, Kyoko had mastered the Equuleus Meteor Punches and demonstrated both courage and strength when confronting the Dryades alongside her comrades. Though her agency is curtailed by the possession, her presence and the bond between the sisters remain the emotional foundation of Shoko’s journey and the core motivation for the struggle against Eris.