Silly boy. You keep taking all these problems on alone. You should learn how to turn to others for help sometime.
~ Index to Touma

Index Librorum Prohibitorum, generally known simply as Index, is the titular deuteragonist and lead heroine of the light novel and anime series A Certain Magical Index, also making a few cameo appearances in A Certain Scientific Railgun. She is a member of Necessarius, the 0th Parish of the English Puritan Church and has an eidetic memory. She holds within herself 103,000 magical texts known as grimoires.

She is voiced by Yuka Iguchi in the Japanese version of the anime and Monica Rial in the English version, the latter of whom also voices May Chang, Mirajane Strauss, Yukari Sendo and Mine Kuramae.


Index is small in stature, has a petite build, and, much to her chagrin, a flat chest. Although she looks like a little girl (and is even called one by Touma), she is actually 15 years old, making her one year older than the 6 foot 7 Stiyl, and only one year younger than Touma. She has thigh-length, silvery-white hair, and large green eyes. She is also often seen wearing her Walking Church, a white, 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. She is noted by Touma to be a "gaikokujin" (foreigner), and it is likely that her nationality is English.


Do I want beef or fish? Do I want beef or fish? Do I want beef or fish? Do I want beef or fish?
~ Index thinking about food (as usual)
Due to being raised in a church and having no memories of her life up until a year before she met Touma, Index is quite innocent and naive, often being elated by things that an adult or even people her age would find mundane. She is slightly ignorant and curious of modern technology, not knowing what a touchscreen was or how it worked until Hyouka Kazakiri showed her. She is a very cheerful and optimistic young girl, even after many years of having her memories erased annually.

Index can be easily irritated especially when it comes to Touma, who usually ends up angering her in some way as a consequence of his own bad luck. He is often bitten by Index as punishment. It is a recurring gag for Index to bite Touma whenever he has inadvertently annoyed or irritated her in some way, occurring even in serious situations or in front of important persons, or out of anger for putting himself in serious danger and making her worry. She has even bitten him out of anger for trivial things that he has not even done, due to her tendency to jump to conclusions. At one point, Touma even compares her to a mosquito. However, in Toaru Majutsu no Index no Subete, it is noted that it is a sign of affection towards him, as Touma is the only person whom she bites. Index can also be rather bratty at times, often getting annoyed when when Touma doesn't spend enough time with her.

Index is also a freeloader, due to the fact that Touma is the one who does all the work in the dorm room, while all she does is eat, sleep and watch TV. While this makes her come off as lazy and greedy, it is not without justification; due to having virtually no memories other than the knowledge of the grimoires, she has absolutely no domestic skills, which is shown when Touma gets tired of her freeloading and tries to get her to earn her keep, only for her to nearly start a fire while cleaning the bath.

Although she can be irritable at times, Index is usually very gentle and polite, not just with Touma, but with people in general. She has a kind nature, as shown when she picked up a stray kitten and took it home, although Touma initially refused. Despite often getting annoyed at Touma for his martyr complex, she also has the trait of sacrificing herself for the sake of others which is why several people befriended her in the past who still keep caring for her despite her memory loss each year. She even attempts to get Touma to stay out of matters involving her church, insisting that she has to solve the problem herself, despite Touma being objectively the better fighter. However, this is partially out of concern for him, since nearly every major encounter with a magician results in Touma getting landed in the hospital. Index is also extremely intelligent, bordering on omniscience, as a result of having the knowledge of 103,000 grimoires stored inside her. Due to her photographic memory, Index is able to remember everything in the books and often gives Touma exposition when needed.

Index also has an extreme appetite, as shown when she met Accelerator and made him to spend all of his money treating her to food. In fact, the very first thing she said to Touma was that she was hungry. She also thinks out loud about what she wants to eat when she and Touma are on a plane to England. Index has taken a liking to the anime Magical Powered Super Android Girl Kanamin and once cosplayed as her. She has strong feelings towards Touma and even confessed her love after knowing Touma lost his memories because of her, however he avoided answering by changing the subject of the talk since he has no idea about what kind of feelings he used to have with Index.


Her sorcery name is Dedicatus545, "The dedicated lamb protects the knowledge of the strong". As the vessel for 103,000 magical books, she is unable to use conventional means to cast spells; instead, she can only use abilities which intercept opponents' spells. Since magic books that are poisonous to the mind. This made Yamisaka Ouma wonder if Index is even human.

  • Perfect Memory: Index is capable of perfectly memorizing anything.  She can remember and recall everything that she has ever experienced, encountered, or learned in her lifetime. She needs only to read, hear, or see something once and she will never forget it. Her mind has unlimited storage capacity, and she is able to immediately recall any information she has stored with perfect clarity and  automatically cross-correlate all known information instantly without strain. She's can perfectly mimic observed movements effortlessly She's able to store everything that she experiences in a photographic memory and recall it instantly without the typical human pause for thought. She can memorize entire books, down to exact letters/word used in any part of the book.
  • Instant Analysis: She has powerful analytical skills, able to automatically formulate how to overcome any obstacle. She automatically understand the mechanics behind any issue or concept she faces and knows what must be done to solve any problem. She can examine a 30 fps anime easily, as well as making her able to reconstruct an image on a surface, like a balloon or bottle, even after it is destroyed.
  • John's Pen: According to Index, she is incapable of magic, however, when under John's Pen Mode, she is capable of accessing the grimoires in her memories, including once performing a complex magical ritual that healed her of all her injuries. It is unknown whether or not she was capable of performing magic before losing her memories. Her self-protection system will use the "Feather of Light" to force a reset on Index's own memory should a manual reset fail to be performed.

After Touma negated the runic symbol that was meant to destroy her mind, while in John's Pen Mode, she was capable of using several very powerful spells:

  1. St. George's Sanctuary, a high class defensive spell which distorts space-time.
  2. Dragon's Breath, a high class offensive spell that has the same amount of power as the legendary dragon of Saint George. This spell casts a beam of light at the target, destroying everything in it's path. It has been shown to have very long range, like when it destroyed Academy City's satellite that housed the supercomputer, 'Tree Diagram', in outer space. It is also shown that the first level of this spell is enough to surpass the cancelling speed of Kamijou Touma's Imagine Breaker and at it's second level, is enough to blow away Innocentius with ease. The after-effect of this spell is the Feather of Light.
  3. Eli Eli Lama Sabachthani (神よ、何故私を見捨てたのですかエリ・エリ・レマ・サバクタニKami yo, naze watashi wo misuteta no desu ka?, "Lord, why have you forsaken me?") - Is a powerful anti-Christian spell which throws a powerful bloody-red beam of light.
  4. Scarlet Stone of Pexjarva- This spell causes the bones in the target's feet all the way up to his knees to feel a deep pain started to swell up. This feels like the pain from the joints between the bones being forcibly stretched apart. This invisible attack seems to be coming up from the floor and seeped into target's body from there.
  5. Sulfur Rain will Scorch the Earth- A area spell attack which throws about 50 arrows appearin from above which strucks down like guillotines piercing and burning through the target. Just an arrow alone is enough to turn stone into dust.
  6. During her stay on St. George's Cathedral while she was being restrain by Stiyl Magnus she grows crimson wings which is said to be angelic wings, with them was enough to dissipate Innocentius and blow his user away with just flapping them.
  7. She also displayed the ability to summon legendary weapons and artifacts creating multiple copies of the same and use them to attack, all of them 'being able to suffocate the enemy just by floating in the air', some of the weapons mentioned are:
  8. The Sword the Harvest God Freyr or Sword of Victory, the magic sword of the god from the Norse Mythology, which fights on its own "if wise be he who wields it" and was stated its wielder has never suffered defeat.

She can also cast two other magical abilities that don't consume any mana energy whatsoever:

  • Spell Intercept, it uses notarikon codes to hijack the spell formula that the caster has been conjuring in their head and causes the magic to go berserk or be outright cancelled. Index used this ability against Sherry Cromwell's golem and to save Last Order from the computer virus that forced her to manifest 'Fuse=KAZAKIRI'.
  • Sheol Fear, is an ability in the form of choir that points out and impeaches the contradiction of the basis of the religion or theory of magic that has been cast and causes a break down in the enemies mind. Although this can be bypassed if the intended target cannot hear it when the Agnese Force nuns jabbed their own ears to block off the sound.

List of Books in Index

There are 103,000 grimoires hidden within Index's memory, however there are only a few instances where the names of several books have been explicitly stated. Strangely, fictional grimoires in reality are real and are part of Index's representative grimoires in the series.


  • Index is still wearing her Walking Church, even though it has lost its powers.
  • Index's 'Dragon's Breath' is one of the few magical attacks shown so far that is able to surpass Touma's Imagine Breaker's cancelling 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.
  • 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.
  • Index is also the first and only girl known to kiss Touma (by the cheek) when she intended to bite him during the Daihasei Festival Arc.
  • Index's bust size has increased a little bit as evidenced in one of the illustrations of Volume 16.
  • Touma has pointed out that she is a sleep walker, and that will always tuck into the futons of others if she is just left alone. This is the main reason of why Touma locks himself in the bathroom every night.
  • 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 sophisticated 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 for some unknown reason Index holding a green onion. It is currently unknown what the intentions of J.C. Staff was on this matter. Probably a reference to Vocaloid's Miku Hatsune.
  • Episode 13 of Mayoi Neko Overrun! featuring Umenomori Chise (who has same voice actress with Index) commenting how Takumi the main character born with misfortune and how Fumino possess right hand that negate luck using Index like voice.
  • 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 want to choose as his lover among all Index characters.
  • In the fourth season of the anime Zero No Tsukaima, the female lead, Louise de La Valliere, as well as several other characters, wear an outfit that is identical to Index's. Also, Louise has a flat chest, and is known to hurt the male lead, Saito Hiraga, when angered by him. Notably, Saito and Louise have the same Japanese voice actors as Shiage Hamazura and Agnese Sanctis.
  • In an unofficial interview, the creator of the series had admitted that Index herself is actually based off of a real life girl that he once knew. She had perfect memory like Index in the series and was very kind. Unfortunately, she died at the age of 17 due to a brain tumour so he made Index in honour of her memory.


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