Katya is a saintia of Saintia Sho's manga. Her story as a villainess is short.
Katya was a young orphan sent by Saori Kido, to bring a cloth, brass, and thus turn his bodyguards. She got the Corona Borealis cloth. However, Katya was brainwashed by a Dryad seed, and because this, when the pope saved her from this same dryad, just thinking that the pope was a good man and decided to betray Saori Kido.
She is sent to the Japão, to kill Saori Kido, but, Mayura, after a fightwith her, purifies her mind.