BackgroundSamhain Festival as well as to win the Luna Nova Cup broom relay. Behind this exterior she harbored a great dream, to become the world's greatest witch by breaking the seal on the Grand Triskellion and obtaining the world reconstruction magic. She was crushed when Chariot instead of her was chosen by the Shiny Rod for this task, but she appeared to forgive and even support Chariot, telling her to accept her destiny. At some point she developed a spite towards Chariot which she would continue to hold deeply. While Chariot became a magic idol, Croix sought a means to achieve a way so that the magic was not forgotten as well as to obtain the Grand Triskellion for herself. This led her to experiment with the emotional energy of people. When Chariot was in need of more exciting magic for her shows, Croix offered to use the Dream Fuel Spirit that turned people's dreaming power into magic without revealing that this It also caused people to lose their magic. When Chariot discovered the truth, Croix reprimanded her for her actions as Shiny Chariot that put magic in vengeance and affirmed that she should not have been chosen. This eventually led to their separation.
Croix witnessed the last Chariot show in which she used a variant of Shiny Arc and ended up damaging the moon. Croix erases the memories of all the audience, leaving Chariot and herself as the sole witnesses of the incident. This development and her eventual falling out with Chariot guided her over the subsequent course of her life. She devoted herself to obtaining the ultimate power through her own means, making pioneering developments in combining magic with modern technology along the way.
When she heard that the Shiny Rod had revived for Akko, she returned to Luna Nova.
Croix along with her group appear as victorious participants in a previous broom race, in one of the photos seen in the winners' showcase.
She appears watching Samhain Festival's final standing in one of the towers of Luna Nova, grabbing a levitating mechanical cubic thread in her hand.
When one of the panels insulating magic from the Sorcerer's Stone was about to fall directly towards Akko, with one of her mechanical brooms, Croix saves her and stands in one of them, offering to talk about the "future" of magic and introducing herself as the teacher of Modern Magic.
During the negotiation meeting, when Headmistress Holbrooke talks about creating functional magical energy for the Academy, Croix comes forward suddenly, offering her invention called "Sorcery Solution System" to get all the magical energy of the Ley Lines and make Luna Nova functional again. Although later, her proposal is undoubtedly rejected by Finnelan in defending the magical traditions. After the meeting, Croix observes Akko in one of the corridors, offering her to go to her Modern Magic's class to know more about it.
When the academy's spirits suddenly acquire an aggressive attitude toward students and staff because one of them was attacked, Croix reassures them by using a technological spell with her invention "Sorcery Solution System" and even resurrects the wounded spirit. After the headmistress approved her ideas to modernize the academy, Croix reveals to have been the one to instigate the revolt of the spirits by sending one of her machines to injure the fire spirit.