Kaori Saeki (佐伯 香織 Saeki Kaori) is a major character featured in the first and second Bible Black eroge games, the anime series Bible Black: La Noche de Walpurgis and its sequel Bible Black: New Testament. She also features in several Bible Black: Only scenes.

An occultist-fanatic, Saeki tries to discover the secret of the Bible Black spell book from her Academy classmate Taki Minase. Along with her witchcraft club friends Jun and Maki she eventually becomes the victim of school nurse Reika Kitami and is put under her mind control spell. She helps the witch carry out her devious plans by kidnapping and abusing her fellow teachers and students.

Some years later, Saeki becomes a teacher at the same school and reforms her magic club with several new students to try and restore the Bible Black. She again becomes the subject of Kitami and carries out her evil orders by torturing and raping her enemies.