Index Librorum Prohibitorum

Index Librorum Prohibitorum (禁書目録 (インデックス) ) is the eponymous character of Toaru Majutsu no Index. Commonly known as Index, she is the main female character of the Magic Side in the Toaru Majutsu no Index series. She is a member of Necessarius and has and is not poisoned by the effects of reading grimoires. As such, she holds within herself 103,000 magical grimoires at the beginning of the series.

Etymology
Her name is based on the book with the same name, or "Index Librorum Prohibitorum" (禁書目録) in Japanese. It is a list of publications prohibited by the Roman Catholic Church.

The avowed aim of the list was to protect the faith and morals of the faithful by preventing the reading of immoral books or works containing theological errors, although it also contained scientific works by leading astronomers, such as Johannes Kepler. The various editions also contained the rules of the Church relating to the reading, selling and censorship of books. It was abolished on 14 June 1966 by Pope Paul VI.

Appearance
Index looks like she is 14-15, one year or two younger than Touma. She is small in stature, has a petite build, and, much to her chagrin, a flat chest. She has thigh length, silver hair, and large green eyes. She is also often seen wearing her Walking Church, a white, and modified nun's habit with gold highlights. It is an accurate replica of the Holy Shroud of Turin and offered Index ultimate protection from most attacks; however, it was destroyed by Touma's right hand. She still wears it, though safety pins are now needed to hold it together.

Background
Much of Index's background is currently unknown because of the periodic memory loss that was brought upon her. Although, Index states that she was born and raised in St. George's Cathedral, there is not enough evidence to corroborate this, as Index as well is unsure of it.

It is not known if 'Index' is her true name or if it is a name given to her because she holds within her the 103,000 grimoires. It is confirmed that Index was specifically chosen as the vessel for the 103,000 grimoires because she has the ability to perfectly memorize things and also because she is unaffected by the books' debilitating effects. She possesses no mana and therefore cannot use the grimoires. She is accompanied by Stiyl around the world in order to memorize grimoires, from the Pataliputra ruins to the Vatican Library.

Later, after becoming the vessel of the grimoires, she was given partners as a means of protection. Three years prior to the start of the series, she was the partner of Aureolus Izzard, then a year later, Stiyl Magnus. Index's relationship with her partners is unknown because of her periodic memory loss, but it is implied that both Aureolus and Stiyl cared for her deeply. In Aureolus' case, he was Index's teacher during his time with her. It is confirmed that Kanzaki Kaori were best friends with Index before Index's memory was erased.

The church told lies to Kanzaki and Stiyl regarding the true nature of Index's memory being erased, as they planned to make the grimoires harder to access as well as because of their fear of Index betraying them or her apparently becoming a Magic God. The church implanted a Collar and a multi-layered program that would disable her from using the magic of grimoires, as such she cannot access her mana, and therefore use magic, normally. To complete this defense, the Collar made Index extremely ill, and required an annual erasure of her memories.

Laura Stuart was the one that came up with this plan, as the alternative was to cut off all of Index's limbs and lock her inside the Tower of London to ensure absolute safety of Index Librorum Prohibitorum's knowledge from magicians that would misuse it, and to prevent her escape.

Index came to Japan a year before the start of the series, although she had already lost her memories prior to arrival, and has somehow awoken in a back-alley with at least basic knowledge regarding her position in the magic side. This was done as part of Stiyl and Kanzaki's plan to keep Index away from magicians that would misuse her knowledge, as Japan was seen to be a place with little history of magic according to them. Both Stiyl and Kanzaki believed it was for the best if Index spent the year running away from magicians as opposed to living through a year full of happiness, as then it wouldn't be as painful (for both themselves and Index) when her memory had to be erased. Index eventually ended up in Academy City as she was being chased by Stiyl and Kanzaki, because it was once again time to erase her memories. Moving from rooftop-to-rooftop during Academy City's unforeseen power outage, she slips and falls, landing onto the apartment balcony of the ever-unfortunate Kamijou Touma.

Toaru Majutsu no Index
Being the main heroine of Toaru Majutsu no Index, Index has a large role in the events of the story, alongside Touma.

Shinyaku Toaru Majutsu no Index
Due to the story shifting focus from magicians chasing her down for her grimoires (though this is apparently still something that occurs occasionally) Index takes more of a backseat role for the Arc which opened Shinyaku Toaru Majutsu no Index only reaching the role she had in Old Testament in the closing of the Arc. Though she takes her role as a main heroine again in the second overarching arc; the Fall of Academy City Arc, aiding Touma in battles and serving as someone he tries his hardest to protect alongside the Magic God Othinus.

Toaru Kagaku no Railgun
Index only makes a small appearance in Toaru Kagaku no Railgun. Apart from her brief appearance in the 2nd opening where she was seen chasing someone (Kamijou Touma), she appears in episode 17 of the anime where she met Tessou Tsuzuri during her patrol. Here, she introduces herself as a sister and not a student and is seen fighting against a cleaning robot who "ate" her donut. She later appears in episode 19 when Touma is looking for her. Her appearance in this part is somewhat obscured though she is seen eating food prepared by the Tokiwadai Dormitory for their visitors, and it is implied that she is the glutton that Tsuchimikado Maika was referring to earlier in the episode.

She is last seen in the epilogue of the last episode of the anime where she is drinking a soda with Touma.

Sisters Arc
While Touma was hospitalized, Index is seen running to the hospital and into his room.

Dream Ranker Arc
Index's nun cap was the only thing shown as she was looking for Sphynx and later finds him after he scares a crow into dropping the Indian Poker card that carried the Breast Upper in it.

Toaru Majutsu no Index: Love Letter Competition
Bundled with Rainbow Spectrum Colors, the short story focuses on Kumokawa Seria's attempts on finding out a spy, by sending out a fake love letter to be delivered to Touma during a time when he is absent. This causes a ruckus with people who are familiar to him.

Index receives the blank envelope after Hyouka delivers it to Touma's address after it has done much travel. Index opens it up to discover that the envelope is empty.

Toaru Majutsu no Index: Road to Endymion
Index supports Touma throughout the short story. She is the first one to notice the strange spell set-up around the city, and is invaluable during their attempt to save as much information regarding the cabal that has infiltrated the city as they can. She aids Touma in the final battle as she analyzes the magic that is used by Ureapaddy Exica against him.

Shinyaku Toaru Majutsu no Index SS
Index is the primary protagonist of the short story. After being given money by Touma after solving several puzzles from a reward site using his account, she is determined to buy Touma a gift that can make her happy. Here, she meets Mikoto and Kuroko, infuriating the former with her antics, reuniting with Hyouka, as well as being aided by Maika on what she should buy for Touma, ending with a steam oven to be delivered to Touma’s dorm.

She later meets an Egyptian magician named the Priestess of Bastet, who has reconstructed a specific Book of the Dead in Index using various clues that only Index can notice, and wants to extract it from her. Here, Index shows her prowess against the magician without throwing a single attack, using her Perfect Memory, her incredible fast-paced analytical abilities, and backdoor tricks that magicians use to quickly subdue her opponent. However, it is her empathy that beats the magician, as after discovering her goal, she determines that all she wanted was to know more of the person she cared for through that person’s Book of the Dead that was completed using Index. Index has her voice transform into that of the woman that the magician cared for, and ending with the magician satisfied with discovering the person’s feelings.

When Index returns, Touma asks how her day was, ignorant of her adventure and confrontation with a magician. She then says that Touma is going to be happy because his “steam” is coming to the dorm for delivery. Not knowing what she meant regarding the steam oven, Touma becomes confused.

Toaru Majutsu no Index Movie: Miracle of Endymion
Index is a central character in the movie, where she and Touma meet aspiring idol Meigo Arisa in the streets, and become fast friends. They later become embroiled in a struggle between magic and science sides wanting her. Index is later tasked on preventing the plans of Ladylee Tangleroad in coming to fruition along with Touma, as she would bring the world to destruction using the Endymion. She later comes before Ladylee, who is revealed to be 1,000 years old and is searching for a way to die, in her core room, and though she tries to convince Index as they are both "cursed by magic", Index says that she knows that Ladylee will not die using her magic. She later uses her knowledge of 103,000 grimoires to analyze and undo Ladylee's spell, who has become too weak and maddened to stop her, while Shutaura Sequenzia and Arisa merge back into one another to cause the Miracle of Endymion.

Touma later admits to Index that Arisa was not an illusion as his right hand did not destroy her, and along with him, later hears a song only the two of the could hear, believing it to be from their friend.

Toaru Majutsu no Index-tan
Toaru Majutsu no Index is subjected to J.C. Staff's parodying, like ‘’Shakugan no Shana’’, Index is turned to a miniature version of herself albeit with a strange marking on her left eye called Index-tan. In the first sketch Index-tan reenacts her meeting with Touma but is then taken away by a bird and is presumed to have been eaten. Index-tan is later seen eating on top of Touma's head a'la Shana-tan and then proceeded to imitate Shana-tan, Index-tan later urges people to buy the Shakugan no Shana DVDs. During the part where Touma insert his right hand inside Index-tan's mouth to disable the magic within her, Touma says "such misfortune" after being vomited upon by Index-tan. Finally Touma and Index-tan watch a commercial featured by Motoharu and Aogami Pierce, asking Index-tan to be quiet after her amazement.

In the second episode, Touma meets Index-tan again and instead of being taken by a bird she is taken by a cat. When Touma is waiting for Hyouka and Index-tan in a changing booth, he comments on how they are mumbling the song they are singing as to go around copyright laws. When Touma is in the hospital he is visited by Kuroko masked in black clothes (a play on Kuroko's name, as are black-wearing stagehands in traditional Japanese theatre) and Index-tan, who mistakes the antics of Touma's voice actor for his.

Index reprises her role as Index-tan in the third episode, however this time she appears as a homage to the title character of . Touma's meeting with Index is redone but with Index-tan as a squid girl, moreover, after every sketch Index-tan shouts the word "Geso" loudly, as a reference to Ika Musume's verbal tic. The second sketch with Index-tan features a parody Ouma's capture of Index, here, Index-tan makes a social commentary regarding the youth and tradition, specifically, the Bon Odori, while Ouma plays melancholy tune in his lyre (previously his Azusa Bow) before Touma arrives. The final sketch with Index-tan features her with Touma and Agnese-tan with Angelene doing cute things, while she makes derisive comments and being harmful to Touma.

Toaru Majutsu no Index (PSP game)
Index is featured as supportive character in the Toaru Majutsu no Index video game.

Toaru Majutsu no Virtual-On (game)
Index is one of the playable characters in the Toaru Majutsu no Virtual-On video game. Her associated Virtuaroid is IDX-10/3000 "BAL-RlooN".

Eromanga-Sensei
The covers for Toaru Majutsu no Index Light Novel Volume 01 and Shinyaku Toaru Majutsu no Index Light Novel Volume 08, which prominently feature Index, can be clearly seen in several episodes, as both Eromanga-Sensei and Toaru Majutsu no Index share the same light novel publisher, Dengeki Bunko. Index's Japanese voice actress also voices the mother of Sagiri in the series.

Shakugan no Shana
In Shakugan no Shana S, one of the two of Yuji's friends was wearing a T-shirt with the face of Index on it. While another one was wearing a T-shirt with Mikoto on it.

Shakugan no Shana-tan Revenge
Index-tan makes a cameo near the end, inserting herself in one of the sketches Shana-tan performs. Here Index-tan remarks that she is hungry while Shana-tan demands Index-tan to go back to her own show, they argue on how Index-tan was only asked to appear on her show. It later pans out to one of the characters of Shakugan no Shana remarking on the appearance of Index-tan and that she is an amateur (referring to her voice actress).

Dengeki Gakuen RPG: Cross of Venus
Index is an unlockable playable character in the game. Index joins your party after you defeat a fake Stiyl Magnus in the game, unlike many of the other playable female characters in the game, Index is more of support-type character using cards that are used in the game to aid the party.

Zettai Hero Project
Index appears as a boss character in her own dungeon in the game; defeating Index allows the player character to access her costume and allows the player to change their form into that of Index, her character class is "Sister".

Disgaea 4
Index makes a small cameo appearance in the game, when the players cast the Omega Heal spell. Her appearance in Disgaea 4 is actually drawn by Haimura Kiyotaka, the illustrator of the light novel.

Lunatia
Index and Index-tan are part of the NPC characters that will assist the player in the Japanese version of the Korean MMORPG Lunatia.

Lucent Heart
The Japanese Lucent Heart developed by Gamania Digital Entertainment has disclosed that Index, along with Touma and Misaka Mikoto will be added as "selectable skins" for the players to use.

References in other media

 * In Episode 5 of the anime Boku Wa Tomodachi Ga Sukunai, a character named Maria (who has the same seiyuu (voice actor) as Index and is a sister) wears an outfit strikingly similar to Index's.
 * Episode 13 of  featuring Umenomori Chise (who has same voice actress with Index) commenting how Takumi, the main character born with misfortune, and Fumino possess right hands that negate luck using a voice similar to Index's.
 * In the fourth season of the anime , the female lead, Louise De La Vallière, as well as several other characters, wear an outfit that is similar to Index's. Also, Louise has a flat chest and a complex about it, is short, has very long hair, and is known to hurt the male lead, Saito, when angered by him.
 * In the 4th episode of Joshiraku, the main protagonists end up at Comiket during a train ride to Odaiba. As a large wave of cosplayers walk past the protagonists and head towards the train station, one of them is dressed as Index.

Design Evolution
As shown in the preliminary sketch for the first volume of Index, Haimura Kiyotaka drew Index with straight hair according to his own tastes. He later changed it after her description did not match her design, which not only includes her hair but her costume as well. As seen in the below illustrations, Index's gildings was originally designed differently, but was changed later as it looked too Incan.

A notable problem Haimura had was the body size that both Touma and Index, especially in regards to the body and head ratio. It was not until volume 2 that Index's body has been settled into its current form. In his drafts for her design for the manga, Haimura states that Index's design has become rounder and smaller as time went on, referring to his deformed artstyle.

Trivia

 * During the Angel Fall incident, Touma and Index found out that Index has her own Academy City ID, though neither remembers having applied for it. In the novel Touma thought it was possible using sophiscated equipment to obtain data like fingerprint, retina scans, voice imprint etc., though he doesn't know why anyone would do this. It is implied Aleister Crowley was the one responsible after making an arrangement with the Anglican Church to keep Index inside Academy City. Also, in episode 15 of the anime, Index's ID picture showed Index holding a green onion. It is currently unknown what the intentions of J.C. Staff was on this matter. This appears to be a reference to Vocaloid's Hatsune Miku.
 * According to the interview on Kazuma Kamachi featured in "Toaru Majutsu no Index no Subete", the author states that Index is the one whom he wants to choose as his lover among all Index characters.
 * Touma has pointed out that Index is a sleep walker, and that will always tuck into his futon if she is left alone. This is the main reason of why Touma locks himself in the bathroom every night.
 * Index is still wearing her Walking Church, even though it has lost its powers.
 * Index's 'Dragon Breath' is one of the few magical attacks shown so far that is able to surpass Touma's Imagine Breaker's canceling speed.
 * Index is still the only girl to have confessed to Touma, however, Touma avoided answering by changing the theme of the conversation because since he had lost his memories, he had no idea about what kind of relationship he used to have with Index.
 * Unlike the character, the real-life Index had, by the time of its end in 1966, only 4327 censored books, newspapers and illegal publications.

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