The Index is a simple mechanical construct that acts as the physical embodiment of the table of contents belonging to the Book of Eibon.
espite being of artificial fabrication, the Index still possesses a distinct and slightly eccentric personality, this often surfaces in his tendency to reply with the nonsense word "takonimo"*, when answering in the affirmative. Although he acts more like a passive observer to people entering the Book of Eibon, he seems to show some interest in people that likes books, as shown when he inquisitively asks Maka what type of book she likes. He dutifully fulfils his role as an index of the Book of Eibon, guiding the team of Spartoi through the Book of Eibon.
The Index has a vaguely humanoid resemblance in regards to it's general shape but it is here that such similarities end. It's mechanized face comprises of a single curved triangular plate, attached to a substantially large cog, with the more commonly observed facial features being replaced instead by emotionally devoid simplistic swirl patternings. The remainder of the Index's body is concealed under a literal shroud, embellished with various words and a repeating pattern composed from squares and circles, except for the multiple small protrusions that act as it's fingers.
To better function in it's role as a personification of the Book of Eibon's content page; the Index has an extensive knowledge of the book's current contents and, the specific individualities and express nature of each unique chapter that comprise the fundamental structure of the book, even in regards to the particular consequences one may face by entering them.
The Index also exhibits the capability to exert a limited control over the interior realm in which it inhabits, most likely due to it's position and role as a rudimentary element of the book that contains it. The full extent of these abilities has yet to be observed but the Index has been displayed generating portals that can easily transfer multiple subjects from one segment of the book to another, although it should be noted that one can not simply "skim" to the final chapter and must instead grapple with the contents of the other chapters so as to progress in a linear manner to their concluding destination.
Naturally, like many others, the Index cannot stand Excalibur to the extent that a grimace even appears in the center of his normally featureless face when in the presence of the Holy Sword.
As an inhabitant of the book originally belonging to Eibon, there is a suggested but not stated strong connection between the two, as creator and creation. It was revealed that The Index is the book's intelligence was responsible for Noah's actions and his creator.He wants to collect the Kishin so he can teach the world about Eibon and his madness.This makes him the true Third Antagonist.
* This word is derived from "Ikanimo", which is a way of saying "indeed" in Japanese but the word "ika" also means "squid". However, the Index incorrectly states the first syllable as tako ("octopus") instead of ika ("squid") resulting in the nonsense word, "takonimo", that it often uses.
The Index bears some resemblance to a strange creature observed standing upon the shoulder of one of the Eight Powerful Warriors, seen in Chapter 16.
Vova
