The Book of Eibon is a powerful Demon Book and one of the many creations of Eibon. It is explained by Noah that BREW and The Book of Eibon are the wisdom of Eibon — essentially Eibon himself. The Index is the embodiment of the contents and intelligence of the book as well as the creator and mastermind of the Icon he creates all commonly named Noah.
In the manga, after being lost to Eibon, the book was possessed by its internal operator, the Index, and held by its Icon. But the DWMA did keep a manuscript copy of the book. At the end of the manga, the Book was in the possession of Crona, kept within the Black Blood on The Moon. In the anime, the Book is in Death's possession.
Externally; the Book of Eibon's composition doesn't differ much from the traditional construction or representation of a typical hardback, in that the entirity of its contents are bound within the confines of a rigid cover, embellished with various "S" shaped designs. However; befitting the true intentions behind the books existence this simple facade belies the extent of the genius of its original creator, who managed to confine an entirely seperate dimension within this grimoire's pages, successfully decieving all observers to what exactly resides in the depths beyond the physical materials that form its exterior.The Index basically represents the Book's intelligence and is the physical embodiment of it.
The Book of Eibon contains contents regarding the necessary requirements and processes involved in the creation of various dangerous demon tools original devised by Eibon himself. Perhaps unsurprisingly, many of the pages that act as blueprints of the Demon Tools seem to have been taken from the book and scattered throughout the entirity of the world; such extracts are often referred to as "fragments".
- Moral Manipulation Machine: One of the pages of Eibon's Book holds the blueprint for the creation of this insidious machine, which brings down the morals of any victim that is subject to its tortures, helping to incite the first indications of madness. The blueprint was taken by Arachnophobia and evenually used to construct the actual machine; however, the blueprint was eventually taken by Sid during a mission and the machine was subsequently captured by Shibusen after Arachne's defeat.
- BREW: Brew, the tempest, is said to be the most powerful creation of Eibon. It is explained by Noah that BREW and the Book of Eibon function as the wisdom of Eibon — essentially symbolizing Eibon himself. It is currently in the possession of Noah.
- Demon Weapons: Most famously, the Book of Eibon contains blueprints needed to create Demon Weapons. Despite having thought of the idea, Eibon never actually created one. Instead; 800 years before the start of the series, the witch Arachne, following the instructions she found within the book, created a demon weapon by murdering a fellow Witch to use as a sacrifice. Using the witch's soul, which has the power of transformation, Arachne joined together it (the witch soul), an inanimate weapon and a human soul to create a demonic weapon which had the ability to transform from human form to weapon form. Thus, she earned the title of "Mother of all Demon Weapons".
Within the Book of Eibon lies various creatures captured by Noah (Greed) and Noah (Wrath). While some are captured to use to fight battles for the sorcerer, the Idol of Greed has also captured various creatures for the sake of collecting the most interesting of creatures. He intended on capturing the remaining of the Great Old Ones.
The Seven Chapters
If Calculation Spells is used correctly, a portal can be created that allows people to physically enter the world inside the book. Demons or any beings that have been collected by the book are sent into this world.
The world inside the Book of Eibon is inhabited by the creatures that the book had collected along with the Index that acts as a guide and supervisor to anyone who enters the book. The Index also is able to manipulate the abstruse letters and markings of the Book of Eibon to re-form into portals, allowing passage between the chapters.
The book is split into seven chapters, each one representing one of the Seven Deadly Sins. The Index states that at the very end of these chapters lie insanity. If one wants to reach the end, they must each briefly struggle with all the Seven Deadly Sins in each chapter. If they waste their time, their souls would be consumed by the sins and they will fall to madness.
This section of the Book of Eibon acts as an introduction to the seven chapters. There does not seem to be much physical matter in this world, as it is composed of long lines of symbols snaking through a field of white. In this prologue, anyone who enters the book is met by the Index, who guide visitors throughout the book.
Chapter 1: Lust
In this chapter, the people who enter it undergo a drastic transformation as their genders are switched, with each person appearing as a manifestation of everything they find appealing in the opposite sex. The chapter is also inhabited by creatures such as the Succubus that try to seduce people in order to steal their souls. Additionally, the gender change in the individuals is actually carried on even if they have left the chapter. Upon leaving the chapter of Lust, they slowly start to change back to their original gender, but the speed of their transformation depends on their sexual desire. The stronger the sexual desire, the longer it takes to change back.
The world inside the chapter of Lust is made up of a large platform surrounded by large curtains, although they branch out, intertwined like branches of trees. Outside the platform, some ruins can be seen against a cloudy daytime sky.
Chapter 2: Gluttony
Unsurprisingly, the chapter of Gluttony is a world filled with an endless mountain of restaurants and food, intending to attract any hapless passerby with their irresistible smell and taste. It also seems to be inhabited by creatures who are actually edible, such as a giant pig (although it will try to eat people as well). As the location is full of restaurants, good luck cat statues also appear in this chapter.
Chapter 3: Envy
The Chapter of Envy differs from the previous two chapters: whereas in Lust and Gluttony all individuals experience the sin together as a group, in Envy, each person is separated into their own world that is manifested out of their envy. For example, Maka Albarn confronts classmates at the Death Weapon Meister Academy who consider her unsuited to be Soul Eater's meister, while Soul Eater faced a manifestation of his brother, Wes, who asked whether Soul was running away from family pressure.
The inhabitants of this chapter wear faces with crooked, vaguely hairlip-like grins and beady white eyes that mock and belittle the one who enters this chapter.
Chapter 4: Wrath
The world in this chapter has a volcanic setting littered with old ruins and clouds of ash overhead. The red color of the molten lava that flows in this chapter stimulates the anger of those who enter, making even notably calm people irritable. The annoying Holy Sword Excalibur is contained in this chapter, possibly as a hostage, making the experience all the more excruciating.
Chapter 5: Pride
This chapter features an elaborate palace of Arabian or Indian design, looking a lot like the Taj Mahal. The atmosphere is much more peaceful than the chapter Wrath, which helps to soothe the anger of anyone who enters this chapter from the preceding one. However, Excalibur does end up following, and offers his power to allow those journeying through the book to skip to the end, something they contemplate with their inflated pride.
Chapter 6: Sloth
Countless beds and chairs logically make up this chapter, tempting those who enter it not only to sit and rest, but also to stymie their ambitions. The panels of the manga itself are much more scarce and disperse, each literal manga page containing no more than three panels in blank white space at a time, with some of the borders appearing torn. There is also no border around the box introducing the title of the chapter, the letters of the title appearing unkempt and each letter varying in size, suggesting the illustrator's own laziness.
Chapter 7: Greed
In the Greed Chapter, coins and paper money rain, stacking up into piles among countless mounds of treasures and giant Maneki Neko statues.
The Greed Chapter is the last chapter of the Book of Eibon, where the Great Old One of Power opens a portal to allow Black Star to meet with Death the Kid, influenced by madness and desiring to battle the ninja.
It is also in this chapter that visitors feel the influence of their greedy desires, but not necessarily giving into that greed. For example, whereas Black Star announces that he desires power, Liz Thompson realizes that she no longer holds her desire for wealth as high as she does her desire to rescue Kid--and to thank him for coming into the lives of her and Patty.
The hidden section, as the Index explains, cannot be accessed through "an ordinary reading" of the Book of Eibon and may be entered only if its occupant, the Great Old One of Power, permits. However, as an extension of the will of the Book of Eibon itself, Noah was able to deposit Death the Kid into that chapter when the shinigami was proving too difficult to contain in other portions of the book (and had been engaging in re-organizing those contents to suit his focus on symmetry). When Black Star was able to answer correctly that what he desired was to possess power, the Great Old One of Power used its Soul Wavelength to open a portal as an "invitation" permitting only Black Star to enter before collapsing upon the ninja's passage.
The interior of the chapter initially resembles a field of white, except for abstruse figures written in lines and swirling around this interior. The white space allows occupants to feel like they are freefalling or hovering, depending on their desire.
This white interior remains until the Great Old One of Power reshapes the terrain allowing occupants such as Death the Kid and Black Star to be surrounded by the Old One's very mass, making occupants feel like they are swimming yet still able to breathe.
This chapter's wavelength is so powerful as to be thought by Kilik Rung as being madness itself.
Not surprisingly — as it was created by a legendary sorcerer — the Book of Eibon displays various mysterious, powerful properties. These powers can be manipulated by individuals other than Eibon, but to do so requires locating the specific pages for the technique desired. Otherwise, in the hands of capable readers, the book contains vast information about many magical topics.
- Capture: Opening the book can allow its intended captive to dissolve into what resembles a swirl of energy, drawn into the book like a mouth sucking in whatever is around it. At some points when capturing, the edges of the Book of Eibon come to resemble teeth, as if consuming its captive.
- Teleportation: Through the use of a single torn out page from within the book, a person is able to transport themselves instantly to the location of the remaining part of the book. When activated the person is sucked into the page, before it combusts, leaving no remains. After this they are ejected from the rest of the book, and so arrive at their destination.
- Writing: Noah can take a pen to the pages of the Book of Eibon, which for any inhabitants or visitors to the book appear as writing above their heads, as when Noah sends a message to Giriko in the Sloth Chapter.
- Summoning: By keeping the book open at a particular section, it is capable of summoning worm-like monsters from the confines of this book. These creatures are strong enough to easily overpower Mosquito and pierce his body with their teeth. They are also able to fire a large explosive beam from their mouths, so powerful as to kill Mosquito in his most powerful form with a single blow.
- Restraints: By placing a particular page above an opponent, magical shackles extend downwards, that are able to restrain and contain even a strong opponent's hands.
- Indestructable Durability: The Book of Eibon is a powerful Demon Book, unable to be conventionally destroyed. Even the power of Death the Kid's Parent's Seven Rays Soul Resonance and Asura's Shinigami Shock Waves didn't damage the book.
The Index was responsible for creating the Icons, a group of artificial beings to serve it and if a Noah dies a new Noah will be created. They are created through embodiments called Icons.
- The arrangement of the interior contents/chapters of the Book of Eibon shares various similiarities with the structure of the Inferno and Purgatorio featured with Dante's Divine Comedy, due to their equivalent fundamental basis being Christianity's Seven Deadly Sins. The 7 Sins correspond to each chapter in which they become worse as the chapter gets deeper.
- An extract from a page found within the book "Alice's Adventures in Wonderland" is observed in the background of the panel where the 7 chapters are initially introduced.
- A manuscript of the book, is kept in level 4 of the Shibusen library, which can only be accessed by Death Scythes and their respective senior Meisters. Maka Albarn was able to access this book using her father's Death Scythe identification card, although she signed the book out under the initial "M." This secrecy alerted Death the Kid, who suspected "M" referred to Medusa, then Franken Stein, who informed Death that Maka had taken the manuscript.
- The Book of Eibon is based off a similar spellbook with the same name from H. P. Lovecraft's Cthulhu mythos. This version of the Book of Eibon was written by Eibon, a character who first appeared in Clark Ashton Smith's Hyperborea stories and referenced repeatedly in Lovecraft's own stories. Smith and Lovecraft's Book of Eibon chronicles Eibon's life and includes his magical formula.