The Mystic Archives of Dantalian (ダンタリアンの書架, Dantalian no Shoka, lit. "Bookshelf of Dantalian"; alternate title Bibliotheca Mystica de Dantalian) is a Japanese light novel series written by Gakuto Mikumo and illustrated by G-Yuusuke. The series started serialization in Kadokawa Shoten's light novel magazine The Sneaker on February 29, 2008. A manga adaptation by Chako Abeno started serialization in Kadokawa Shoten's shōnen manga magazine Shōnen Ace on March 26, 2010. Another manga adaptation by Monaco Sena started serialization in Kadokawa Shoten's seinen manga magazine Comp Ace on March 26, 2010. A 12-episode anime adaptation by Gainax aired between July and October, 2011.
 This story takes place in England after World War I. After the death of his grandfather, Hugh Anthony Disward, also known as Huey, receives a mysterious key and according to his grandfather's will, must take custody of the Bibliotheca Mystica de Dantalian in order to inherit his estate and all his possessions. Upon meeting Dalian, a child living at the estate, he learns that she is the guardian of the Archives which contain forbidden knowledge stored in thousands of magic books called "Phantom Books" (幻書, gensho). Upon agreeing to become Dalian's new Keykeeper, Huey joins her into investigating incidents regarding people misusing the power of the Phantom Books, most of them with tragic consequences, and using his power as Keykeeper to seal the power of the Phantom Books and restore order to the area.
 Between February 29, 2008 and February 28, 2011, eight light novels were serialized in The Sneaker. They were subsequently published under Kadokawa Shoten's Kadokawa Sneaker Bunko imprint, with the eighth volume released on July 1, 2011.
 The Mystic Archives of Dantalian has received three manga adaptions, all of which have reached completion. The first, sharing the name of the novels, began serialization in Shōnen Ace on March 26, 2010 and ran for five volumes until July 26, 2012. The second, Dantalian Days, began serialization in Comp Ace on March 26, 2010 and ran for two volumes until October 26, 2011. The third, a yonkoma spinoff titled Dalian-chan no Shoka, began serialization in 4-koma nano ace on July 7, 2011 and ran for one volume until July 9, 2012.
 In June 2010, Kadokawa announced that an anime television adaption was being developed. Produced by Gainax under the direction of Yutaka Uemura, The series aired its broadcast run on TV Tokyo from July 16, 2011 to October 1, 2011. The series is also streamed with English subtitles by the media websites Crunchyroll and NicoNico. The opening theme is "Cras numquam scire" (To Never Know Tomorrow) by Yucca (feat. Daisuke Ono) while the ending theme is "yes, prisoner" by maRIONnetTe. Funimation has licensed the series for North America and released the series on subtitled DVD on February 14, 2017.
 An OVA, "Ibarahime", was produced as a cross-promotion with the release of the manga The Mystical Archives of Dantalian, volume 5.
 Dalian is currently reading a trilogy by the name of "Crown of the Dog Days," but she is enraged with Huey for only ordering the first two books. Huey explains that the author, Lenny Lents, was killed before he could write the last installment, and tells her of a letter written by the author to his grandfather requesting for his help, claiming to be imprisoned by a bizarre book. They arrive at his estate to find a woman named Paula Lents, claiming to be his wife, washing a bloody machete. She tells them that Lenny is currently writing the last installment in the series, and to return the following day, so they could prepare for their visit. However, as Huey and Dalian inspect her garage later that night, they find the dead body of Lenny Lents. They decide to further investigate the matter, certain a Phantom Book is the cause of the problem.