After she is rescued by Steiner from "alter egos", who killed her younger brother, she asks Steiner to make a contract with her to make Steiner stronger. Her childlike appearance is the result of a mutation caused by her contract with Steiner; it severely slows down her physical growth and aging process. As a veteran contractee, she has gained considerable experience and a keen insight. She possesses several combat accessories called "thousands", but only two are shown in the manga. One is the Hex Ring she wears to create the Hex Shield which blocks attacks. The other one is the ring she gave to Keita.