An eighteen-year-old Japanese sorceress from Necessarius. Unlike her partner Stiyl, she uses magic to magically strengthen her body. Her sorcery name is Salvare000, "Be the salvation of those who cannot be saved" (Sukuwarenu Mono ni Sukui no Te o). She uses a two-meter-long nodachi called "Seven Heavens Seven Swords" as her weapon. She has a special attack called Nanasen ("Seven Flash") that uses her sword and some wires. She used to be a kind woman who treated Index like a sister, but when Index's memories were deleted by Necessarius, Kaori changed into a cold and silent woman as Index no longer remembered her and consequentially did not trust her. After Tōma saves Index's life and her current memories, she decides to let Index stay at Academy City as she feels Tōma can protect her.