From one of the highest-grossing adult animation series of all time comes the game that started it all. There is a legend on campus of an underground room where debaucheries and magic rituals once took place. The room was supposedly sealed off after a human sacrifice. As the thirteenth anniversary of this grisly event draws near, someone is plotting for history to repeat itself. Minase is a mild-mannered junior who never thought twice about magic or campus legends, but then he finds the mysterious "Bible Black". Will he be tempted by the dark path of debauchery, or will he use his power to stop the upcoming sacrifice?