Magical Girl Lyrical Nanoha Wiki
Magical Girl Lyrical Nanoha Wiki
Book of Darkness
Book of Darkness
Device profile
Other namesBuch der Dunkelheit
Tome of the Night Sky (true)
Buch der Nachthimmel (true)
MasterHayate Yagami
Magic systemAncient Belka
TypeUnison (Lost Logia[1])
HandlingAuxiliary control
Japanese name闇の書
(Yami no Sho)
First app.A's manga (prologue)
Last app.A's (ep.13)
Voiced byAlexandra Haefelin
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The Book of Darkness (闇の書 Yami no Sho, officially/Ger. Buch der Dunkelheit) is an ancient Lost Logia that had been under Administrative Bureau's investigation several years prior to the events of Magical Girl Lyrical Nanoha A's and The MOVIE 2nd A's.


The Book of Darkness appears in A's and its movie version only. It is first seen on Hayate Yagami's bookshelf in chains. Except for its slightly-extended appearance in the portable continuity, the tome with same outlook seen in later series (after 0066) is another Device newly created by Hayate.


The origins of the Book are unknown. It was presumably created before or during the Warring Ages of Belka and originally served as a benign magical storage medium under the name of Tome of the Night Sky (夜天の書/夜天の魔導書 Yaten no Sho/Yaten no Madōsho, officially/Ger. Buch der Nachthimmel).

At some point in the past, however, tampering by curious mages trying to seal away the Tome of the Purple Sky and its Lord Yuri Eberwein caused its Defense Program to be corrupted, resulting in the book becoming parasitic and giving it its common name. From that time onward, it fed off the energy of its masters and eventually killed them if they did not fill its pages with mana from Linker Cores. On the other hand, if they did, the Defense Program would go out of control, kill them, and cause a massive dimensional dislocation before going dormant again in another part of the universe, allowing the vicious cycle to continue. The Book could be destroyed but not for long, as it would regenerate in a few years, beginning the cycle anew.

The penultimate accident took place in the year 0054 of the New Calendar. The TSAB task force managed to secure the Book but it then went out of control and Admiral Clyde Harlaown sacrificed himself and his ship to stop its rampage. The final Book of Darkness incident took place in 0065. During the incident, the entire book was reprogrammed by its final master, Hayate Yagami, purging it of the Defense Program, whose core was destroyed by the Arc-en-ciel of Arthra. To stop the Defense Program from regenerating once and for all, the Book's Master Program also had to sacrifice herself.


The Book of Darkness may be more accurately described as a collection of artifacts and technologies. In addition to the Book itself, which is a storehouse for stolen knowledge and spells, it also includes different components.

Unless the Book's pages are filled with Linker Cores, the Master Program can only communicate with her master telepathically. Full (non-material) manifestation of the Master Program's personality is possible after at least 400 pages have been filled. The complete physical manifestation and Unison Device functionality are only accessible after all 666 pages have been filled.[2]

The whole Unison Device is reprogrammed and renamed upon Hayate's awakening in A's episode 11. Components of the whole set of Unison Device, before and after the reprogramming, are as follows:

Component Before reprogramming After reprogramming
Master Program
The Master Program is nameless and generally known as "the Will of the Book of Darkness" (闇の書の意志 Yami no Sho no Ishi). She is responsible for mana-control and ignition of the Unison with the Book's Master. Separated from the Book of Darkness and continued to be the Master Program of the new Unison Device "Reinforce".[3]
Defense Program
The Defense Program is capable of regenerating the book infinitely. It was originally designed to protect the master and the Book content, as well as to back-up collected data. This part is not incorporated into Reinforce. However, even upon its total destruction in A's episode 12, it could still be recovered in a few days, had Reinforce (its "root") not self-destructed.
Guardian Knight System
(守護騎士システム officially "Das Schutzrittersystem")
Better known as the Wolkenritter, their existence began with the first awakening of the Book of Darkness in the past. They collect mana for the pages and protect their master. Upon the recovery of their Linker Cores, they are separated from the Book of Darkness and thus do not need to be destroyed together with Reinforce.
The Book The Book itself has 666 pages and collects data. Upon completion (and Unison with its Master), it becomes a storage,[1] serving as a complement to the Master Program. The Book, without any AI, becomes part of the Unison Device "Reinforce" along the Master Program,[3] in its original name Tome of the Night Sky. It is later destroyed along with Reinforce, and Hayate later creates a new Tome of the Night Sky as storage medium for her magics and spells.
The Staff The existence of the staff was not known prior to Hayate's reprogramming of the book. Appears as (or becomes) part of the Unison Device "Reinforce",[3] named Schwertkreuz. It is presumably destroyed along with Reinforce, and Hayate later creates an identical staff to replace it.
The Fragment/
The Pendant
N/A The sole inactive "sword cross"-shaped piece remained after Reinforce's destruction, without any function. It is used by Hayate as the standby form of her new staff some time later. In the movie version, the left-over item is a pendant of that fragment.
Guardian Better known as Yuri, she was created by an archaeologist who have a full knowledge about the Ancient Belka stuffs in the past.[4] Her existence is to protect the book and prevent the Defense Program gone berserk. N/A
The Language Translation The book has a ability to translating the Master and Guardian's language into another language. N/A


  1. ^ a b Magical Girl Lyrical Nanoha A's, DVD Device Card - Buch der Dunkelheit.
  2. ^ Magical Girl Lyrical Nanoha A's Sound Stage 02, track 8.
  3. ^ a b c As a Device, Reinforce consists of the Master Program Unison Device, the Book, and the Staff. (Magical Girl Lyrical Nanoha A's, DVD Device Card - Reinforce)
  4. ^ Magical Girl Lyrical Nanoha Detonation fifth bonus weekly movie