Story: After their rejected request to create a formal student magic club, Hiroko Takashiro, Saki Shidou, and Rie Morita are to continue practicing witchcraft in their free time only. One day, Rie comes across a dusty, hand-written book. Found on a sales pile in an antique shop, the manuscript seems to be nothing more than a foreign curiosity.
Upon translating the book, the girls discover simple spells designed to bend an unsuspecting victim to the user's will and impose one's sexual desires on them. Realizing they have come into possession of a mighty weapon, the group begins fulfilling different requests of other students—be it for love, vengeance, or sexual desire. As the situation spirals out of control, the magic club gradually transforms into a cult of , lust, and human sacrifice.
Every school has secrets, but few leave a stain that won't wash out. In a certain school, there was once a fun club centered around magic but had turned into and a lust for power. Sealed and willfully forgotten, the resulting evil of that day remained chained in the school's basement. Twelve years later, high school student Taki Minase, while inspecting the place where the incident took place, uncloaks the secret plastered in —a book of magic called "Black Bible." Trying his luck with its love curses, he soon finds out the magic proves real and easily penetrates the hearts and bodies of his fellow classmates.
The resulting intercourse leaves the student body very vocal, and Minase's acts do not go unnoticed. What was at first a simple stroke of curiosity becomes much larger and harder to control. Fully swallowed by the unshackled darkness, everyone he knows becomes a victim, including his friend Kurumi Imari. Torn apart, Minase finally realizes his mistakes and that he must reverse them in time if he ever hopes for him and Imari to come together.
Several years have passed since the Walpugis Night incident and several bizarre serial cases have occured in the metropolitan area. bodies of couples are discovered 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.
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