Index

Index(インデックス Indekkusu) is the eponymous character of Toaru Majutsu no Index. Also known by her full name of Index Librorum Prohibitorum, she is the main female character of the series and is considered the main heroine of the Magic Side. She is a member of Necessarius and has a Photographic Memory. She holds within herself 103,000 magical texts known as grimoires.

Background
Much of her background is currently unknown because of the periodic memory loss that was brought upon her. 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, since she possesses no mana and therefore cannot use the grimoires. Though this does not explain how Index can still somehow use magic, it is thought some sort of "programming" in addition to Johann's Pen has been implanted into Index to allow her to use magic without being affected by the grimoires. In the manga it is shown that the ritual of transfer was performed in the Vatican by Necessarius.

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 care for her deeply. In Aureolus' case, he was Index's teacher during his time with her. It is confirmed that Kanzaki Kaori was best friends with Index before Index's memory was erased.

The church told lies to Kaori and Stiyl, as they planned to make the grimoires harder to access by telling their underlings to perform "maintenance" on her mind at one-year intervals once her memory had reached its "limit;" that way, she would not remember her close friends and accidentally or purposely reveal the contents of the grimoires. 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 London's Clock Tower 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. This was done as part of Stiyl and Kaori'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 Kaori 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 Kaori, because it was once again time to erase her memories. Moving from rooftop-to-rooftop during Academy City's unforseen power outage, she slips and falls, landing onto the apartment balcony of the ever-unfortunate Kamijou Touma.

Appearance
Index is small in stature, has a petite build, and, much to her chagrin, a flat chest. It can be assumed that she is very young. She has thigh-length, silvery-blue hair, and large green eyes. She is often seen wearing her "Walking Church," a white, modified nun's habit with gold highlights. It 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.

Personality
She is often elated by things that an adult would find mundane and is slightly ignorant and curious of modern technology. She is usually gentle and polite with people and has a kind nature, as shown when she picked up a stray kitten and took it home, although Touma initially refused. She can be easily irritated in a similar manner to how a child reacts to something they don't like- 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. She also has an extreme appetite as shown when she met Accelerator and forced him to spend all of his money treating her to food. Index has taken a liking to the anime Magical Powered Super Android Girl Kanamin and once cosplayed as her.

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.

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, though in certain episodes she takes more of a back-seat role, as seen during the 'Sisters arc' in which Misaka Mikoto could be considered the lead female.

Index Arc
Index first meets Touma while hanging over his apartment balcony. She remarks about how she is very hungry and would be extremely grateful if he could give her some food. Index introduces herself as a nun of Necessarius and reveals that she is being pursued by magicians, who are after the grimoires that she has. At first, Touma is skeptical of the existence of magic, but is quickly convinced of it as he is able to destroy Index's "Walking Church" using his right hand. After a lengthly discussion, Index decides to leave Touma's house, as she doesn't want him to have to get involved, Touma goes to stop her and Index asks if he would be willing to "follow her into the depths of hell". Touma hesistates at this question and Index smiles to herself before walking out, forgetting her headdress while leaving. Because of this she later has to return to Touma's apartment to retrieve it, but is attacked by Kaori Kanzaki, who seriously injures her, albeit unintentionally.

Touma returns home in the evening to find Index covered in blood and unconscious outside his front door, he is then confronted by Stiyl Magnus and a battle ensues. During this battle against Stiyl, Index falls under Johann's Pen Mode. She aids Touma by telling him that Stiyl has placed runes all over the building to aid him. Touma quickly deduces a counter-measure and Stiyl is defeated. After Stiyl's defeat, Touma takes Index to Tsukuyomi Komoe's house, as she is not an esper and is therefore capable of performing the ritual to heal Index. Index, still under Johann's Pen Mode, finishes the healing ritual with Komoe by summoning a replica of an angel, while chanting. Afterwards, she falls unconscious.

When Touma later returns, Index tells him of the existence of the Church of Necessary Evil, also known as Necessarius. Later, she and Touma go to a bath together where she reveals that she has lost all of her memories from the previous year. For one reason or another she assumes that Touma is angry about this and runs away. Some time afterwards she discovers that Touma has been beaten to unconsciousness (by Kaori Kanzaki) and that he has been asleep since. Stiyl and Kaori come to the apartment for her, but Index believes that they are after Touma, and she tries to defend him, only for them to leave without trouble, however, they give Touma a time limit, after which they say they will return.

While Index is resting, Touma discovers the hidden mark within her that could destroy her if her memories aren't periodically erased. Touma touches the seal with his right hand and causes Johann's Pen Mode to activate. Index then attacks Touma, as well as Kaori and Stiyl, who have made good on their promise and returned. Kaori and Stiyl discover that they've been tricked by their church into believing that they needed to erase her memories. With the efforts of Kaori and Stiyl, Touma is able to defeat Johann's pen (and in the process, destroys Tree Diagram accidentally) but at the cost of Touma losing his memories.

The next day, Index visits Touma in the hospital, where the 'frog-faced doctor' tells her that his memories have been completely erased. Even so, Index pleads with Touma to remember her in a heart-felt speech, asking him to recall the things that had happened between them recently and even telling him that she loves him. However Touma surprises her by stating that his memories were not really destroyed and that his right hand has fixed the problem. Index becomes upset at him for joking about such things and bites him, leaving shortly afterwards. However, it is revealed that Touma lied about his memories because he couldn't bear to see Index cry.

Deep Blood Arc
Index and Touma go to a restaurant with Tsuchimikado Motaharu and Aogami Piasu where they meet Himegami Aisa. Index argues with Aisa after the latter claims that she is a magician, however, their argument is cut short when Aisa's teachers come to pick her up. When walking home with Touma, she discovers an abandoned kitten and decides to take care of it, much to Touma's disapproval. The cat runs off and she tries to give chase. Suddenly, she notices someone applying a magic spell and decides to investigate, leaving Touma alone. When she returns to Touma's apartment, she is carrying the kitten with her and has decided to name it Sphinx. Touma disapproves at first, but eventually relents and allows Index to keep Sphinx, much to the her delight.

After Touma again leaves, Index eats the pudding in Touma's refrigerator, when Touma calls her he scolds her for it but suddenly disregards it. Later when Index is taking a bath she remarks on how Touma became distracted about something when discussing the pudding and decides to go find him. Index later arrives at the Misawa Cram School where she meets Aureolus Izzard, and although he is familiar with her, she has no idea who he is as her memories of him were erased. Index is later struck unconscious and sleeps through the whole battle between Aureolus (who is planning to turn her into a Vampire)and Touma, somehow dreaming blissfully of Touma and complaining to him of her hunger.

Index, along with Aisa and Sphinx, later visits Touma in the hospital. She tells him that the church is going to take care of Aisa from now on. She proceeds to eat the apples that Stiyl gave to Touma before Sphinx wreaks havoc in Touma's hospital room.

Sisters Arc
Index and Aisa try to find ways to get rid of the fleas that are infesting Sphinx until Touma comes home along with Misaka 10032, much to the jealousy of Aisa and Index. Misaka 10032 helps get rid of the fleas on Sphinx using her electrical abilities and proceeds to lecture Touma on how he should disinfect the room against more fleas before leaving. Later on, Index and Aisa decide to go to Komoe's house for food, seeing as Touma has yet to return home. During their time there, Index helps herself to food as Komoe explains to both of them how esper abilities work using Personal Reality. Komoe uses a chocolate ball inside of a box to demonstrate this to Index, who is frustrated at not being able to figure out what the box holds.

They later go to a public bath, drink milk and enjoy massage chairs. Komoe continues to explain to Index and Aisa about esper abilities and the strange occurence of Level 0's in the city. She also inadvertently reveales that many "naughty" things happened with Touma in the past while blushing heavily, which irritates Index and Aisa.

After Touma's battle with Accelerator, Index once again visits him in his hospital room. She gets upset and bites him for trying to go it alone and not asking her for help. This is followed up with a loving hug, and Index tells him how she worries about him and that the next time he fights, he should come to her first. Index asks him what he fought for this time, and Touma says that he fought for himself.

Angel Fall Arc
At Komoe's insistance, Touma and Index go to the beach for a vacation to lay-low until the heat on them from the "higher-ups" dies down. Index shows off her new swimsuit to Touma and gives him a jellyfish to the face, confusing it for a hat. Index later becomes disappointed when she discovers that the arrival of Touma's parents has been delayed, but Touma calms her down.

When everyone's physical appearances are switched due to Angel Fall, Index switches appearances with Aogami Piasu, much to Touma's horror. For the most part of the arc, Index gets abused by Touma for looking like Aogami Piasu and coming on to him. When they return to normal, Index derides Touma for her abuse at his hands and punishes him as-per-usual by biting him.

====Three Stories Arc ====

The Fake Date and the Kamijou Faction
While Touma is on his fake date with Mikoto, unbeknownst to Index, she is watching an anime called Magical Girl Kanamin intensively until Touma calls her, asking her if she is alright and informing her that a magician is in the city. She aids Touma by telling him the nature of the weapon the magician is using. Touma is cut-off from her before she can berate him again.

Accelerator and Last Order
Accelerator passes by Touma's dorm building while Index and Touma are arguing during the early hours of the morning. He blocks the sound out with his vector manipulating powers.

Yamisaka Ouma
Index and Touma go to a diner. Touma is working on his homework, and Index lectures him on it. She reveals that what he is studying is a veiled occult book and one of the 103,000 grimoires contained within her, before being attacked by Yamisaka Ouma. Despite Touma's efforts, she is kidnapped by Ouma.

During her captivity, it is revealed that Ouma is trying to pull a book from her that will cure any sort of ailment which he needs because of a woman he had fallen in love with. Index pleads with him to stop as the spell would be harmful to Ouma himself, all the while Touma hears the events unfolding using the cellphone he gave to Index.

Touma arrives just in time and stops the ceremony before any further damage could be done to Ouma. He proposes to remove the curse of the woman Ouma fell in love with using his right hand.

Kazakiri Hyouka Arc
Index follows Touma to school because she is worried that she will not get any lunch due to the refridgerator being empty and Touma not being back until the evening. She successfully finds Touma's classroom but is then swiftly told by Komoe to go home. Index meets a mysterious person named Kazakiri Hyouka, who helps her to use a vending machine. They become fast friends and Hyouka helps Index fit in by giving her a school gym uniform to wear. Their fun is cut short when Touma accidentally walks in on them getting changed. He is once again bitten. Index introduces Touma to Hyouka and tells him that they are friends, she also warns Hyouka of Touma's tendency to attract women before they are interrupted by Komoe. Hyouka then suddenly disappears. Index is later seen depressed because she believes that Touma is angry with her and that he hates her. Hyouka, however, consoles her and tells Index that Touma is angry because he cares about her and because Index is his friend. Touma finishes his classes and keeps his promise to go somewhere with Index, he also invites Hyouka to come along.

Index is very enthustiastic when they visit the underground mall. The three of them eat and also play games, and once again, Touma accidentally sees them changing clothes, which Index promptly punishes him for. Their fun is put to an end when they are forced to evacuate due to a disturbance in the underground. They learn that it is the work a magician. Touma decides to protect everyone with his right hand, but Index is against this, believing it is her job to go against magicians. When they hear footsteps approaching, Index and Touma trip over each other. Index then meets Misaka Mikoto for the first time but due to both girls affections for Touma they do not get along very well. Both girls demand answers from Touma on what his exact relationship is with the other. Touma asks Kuroko about the situation and learns that there is a terrorist in the underground mall and that, as a member of Judgment and being a teleporter, it is her duty to evacuate civilians. Touma asks Kuroko a favor- to teleport Index and Hyouka away but Index disagrees because it would mean Mikoto being left alone with Touma. Touma then asks Kuroko to teleport Hyouka and Mikoto but Mikoto then disagrees since that would mean Index would be left alone with Touma. Because of this, Kuroko is prompted to teleport both Index and Mikoto away.

Later, outside, Mikoto and Index complain about the hot weather. There, Mikoto asks Index why she is wearing a habit in such heat and then asks why her garment is secured with safety-pins, to which Index replies that she doesn't want to remember how it got ruined. Suddenly, Sphinx runs away and prompts Index to give chase, leaving Mikoto behind. However, Index comes face-to-face with the golem of Sherry Cromwell, whose target is now Index. Even though Index cannot perform magic, she is successful in holding back the golem by intercepting the commands given by Sherry to the golem using the safety pins from her clothing. However, the golem begins to act on its own and begins moving automatically, making Index's situation grim as she can no longer disrupt the golem's movements. Index is saved by Hyouka who reveals to Index that she is not really a human and states that "only monsters should fight other monsters". However, even with Hyouka's vast amount of power she is unable to hold-off the golem, and the two girls are eventually saved by Touma who finally destroys it for good.

Index later confronts Hyouka about her not being human and hugs her, confirming to Hyouka on Touma's statements that she is still human regardless of what she believes herself to be. After a talk about the untrue nature of Touma's powers, both she and Hyouka conclude that Touma's power can't be classified as magic or esper. Index then says her farewells to Hyouka as she returns to the Imaginary Number Sector. She tells Index that she will always be at her side, even if Index can't see her and promises to meet Index again one day before fading away.

Orsola Aquinas Rescue Arc
At the begin she is talking with Tsuchimikado Maika, showing her disatisfaction that without Touma on home the thing gets boring and asks Maika why she isn't at her school, then thinks if she becomes a mais she can go with Touma at his school with Maika replying that being a top-class maid isn't easy. Suddenly, Stiyl Magnus appears simulating an abduction in order to force Touma to get out of Academy City.

Meanwhile Index, staying at Hakumeiza, discusses with Styil about the situation concerning the Amakusa Catholics and the grimoire named Liver AL ver Legis with the the first suspected to have kidnapped Orsola Aquinas and the Book of the Law to achieve ultimate power. Then, Roman Catholic Church asaoult team leader, Agnese Sanctis, arrives to join the talk.

Soon as Touma arrives at Hakumeiza along with Orsola Aquinas, the latter is kidnapped once again by the Amakusa Church. But Index suggest there is no need to hurry, as Index judges that Agnese still has little information regarding the Amakusa and suggests that they might use "miniaturized pilgrimage"--a magical transportation technique based on a certain map-- to escape their pursuers. Despite this, Index assures that it can only be done at midnight, meaning that they still have four hours to prepare. Meanwhile, she uses the GPS function in Touma's phone to plot the location of the nearest portal. Index warns Agnese about the possibility of escape once the portal activates at midnight, and Agnese responds by reminding them to flee the scene when they fail to retrieve Orsola by five minutes before midnight. Agnese's forces and her group along with Touma and Stiyl go their separate ways.

For the meantime, they can only rest until the time comes.

The Way of the Light and Darkness (Vol. 12 & 13)
August 31.

Lying on the floor of Touma's room and complaining of hunger, Index makes her displeasure known. Touma tells her the menu will be soumen and noodles, but she starts to complain about that too. Then, when Tsuchimikado calls them to share the food Maika has just made for him, she rushes to Tsuchimikado's room along with Touma. Touma and Index are then seen to devour the food.

Fiamma of the Right and World War III
Later, during her stay at the St. George Cathedral- the Necessarius headquarters, Index grows "Red Wings" and defeats Stiyl Magnus with ease, who tries to restrain her in vain. She succeeds in destroying the headquarters in the process.

Abilities
Her sorcery name is Dedicatus545, "The lamb is devoted to protecting the wisdom of the strongest" (献身的な子羊は強者の知識を守る).

Photographic Memory: She is capable of perfectly memorizing anything, such is one of the reasons why she was chosen as the vessel for the 103,000 grimoires, magic books that are poisonous to the mind. This made Yamisaka Ouma wonder if Index is even human.


 * Johanns_Penmode.jpgn's Pen (自動書記 (ヨハネのペン)): According to Index, she is incapable of magic, however, when under Johann'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 Johann's Pen Mode, she was capable of using several very powerful spells: She can also cast two other magical abilities that don't consume any mana energy whatsoever:
 * 1) St. George's Sanctuary (聖ジョージの聖域 (セントじょーじのせいいき)), a high class defensive spell which distorts space-time.
 * 2) Dragon's Breath (竜王の殺息 (ドラゴンブレス)), 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 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) During her stay on St. George's Cathedral while she was being restrain by Stiyl Magnus she grows Red Wings, though the nature of said wings is unknown it was enough just with flapping them to dissipate Innocentius.
 * 4) 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:
 * 5) The "Sword of Freyr" or Sword of Victory, the magic sword of the god Freyr 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.
 * 6) The Sword the Harvest God, which is a reference to the Norse goddes, Sif, the wife of the god Thor.
 * Spell Intercept (強制詠唱 (スペルインターセプト)), it uses notalicon 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 (魔滅の声 (シェオールフィア)), is an ability 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.

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. Below is a list of the books that have been named thus far:
 * The Book of Eibon
 * The Lesser Key of Solomon (Lemegeton)
 * The Book of the Dead
 * Necronomicon - In reality is a fictional grimoire created by horror writer H.P. Lovecraft for his stories, it is unknown if the same applies to the Toaru Majutsu no Index universe. Seeing as it is one of the books stated that are contained within Index, it is assumed that their version of the Necronomicon is genuine in their universe.
 * The Cannabalism Ritual Book
 * The Nameless Book
 * Momotarou - According to Index, the story is actually of occult nature and was disguised as a simple fairy tale told to children. Hidden in the story is how to make a elixir of immortality, with metaphors of how a peach (magic formula) comes floating down the river between Life and Death and the old couple in the story have regained their youth.
 * The Tetrabiblos
 * Baopuzi - is a grimoire from China with a way to become an immortal written inside it. Within the book is the way to learn Rentanjutsu, it's said a person can create a miracle drug to cure any illness or curse using that technique.
 * Book of the Law - Book written by Aleister Crowley, according to both Laura and Stiyl she can only memorize the undeciphered code within the book and cannot interpret it.
 * The Moon and the Rabbit
 * Time related to Life and Death

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 commerical featured by Motoharu and Aogami Piasu, 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 the hospital he is visited by Kuroko masked in black clothes (a play on Kuroko's name, as kuroko are black-wearing stagehands in traditional Japanese theatre) and Index-tan, who mistakes the antics of Touma's voice actor for his.

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 (refering 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.

Trivia

 * It is a recurring gag for Index to bite Touma whenever he has inadvertently annoyed or irritated her in some way, occuring even in serious situations or in front of important persons.Index_and_a_leek.jpg
 * 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.
 * During her fight againt Shery's golem, the music theme Jellyfish interpreted by Mami Kawada is played as a BGM.
 * Index's bust size has increased a little bit as evidenced in one of the illustrations of Volume 16.
 * 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 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 Hatsune Miku.
 * 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.