Saeki Kaori is a classmate of [Minase](https://anilist.co/character/7752) (protagonist of Bible Black) with a fascination for the arcane arts. She has researched the history of the school&rsquo;s magic club and the ritual held 12 years before the story opens, and when she discovers that Minase is able to use real magic she is determined to find out his secret whatever the cost. Unfortunately for her she finds herself quickly wrapped up in events beyond her control, and becomes one of the first to succumb to the tide of evil sweeping the school.

Based on the erotic game by Active. 
Minase, a high school student, found a book of magic in an isolated room in his school. He started practicing black magic that has extreme sexual effects that benefited him and some of his friends. Intrigued, Minase got deeper and deeper into using the craft, not realizing the evils that will come forth. Eventually, the origins of the book was revealed, and so did the incident twelve years ago on the night of the Walpurgis, the night when the power of evil is at its strongest. After coming to his senses, Minase struggles to get himself out of the darkness that he had put himself into.
 
(Source: Anime News Network)

Based on the erotic game by Active. 
Several years have passed since the Walpugis Night incident and several bizarre serial murder cases have occured in the metropolitan area. Dead bodies of couples are discovered murdered during sexual intercourse. The women didn't have any external injuries, but the men were completely burned and carbonized except one part... their genitals. To solve these bizarre incidents, a special detective team called "Tokken" is deployed. Included amongst the members of Tokken is Imari who had experienced the events of Walpugis Night. While investigating the incident, they found a mysterious phrase, "Spear of Longinus," and a strange cult group that is related to the incidents.
 
(Source: Anime News Network)

Based on the erotic game by Active. 
Bible Black Only explores the sexual misadventures of the supporting cast from the main Bible Black series. Miss Takashiro reminisces on her demonic capture, Itoh reveals her sadistic side, and Saeki is stalked by her classmates. Bible Black Only is a series of stand-alone episodes that do not affect the continuity of the main Bible Black series, and it contains footage that was previously only available on the R2 Bible Black Perfect Collection DVD.
 
(Source: Anime News Network)

Kaori Saeki