Yomikawa Aiho

Yomikawa Aiho (黄泉川 愛穂) is a character introduced in Toaru Majutsu no Index. She is a P.E. teacher at A Certain High School, and is good friends with fellow teacher, Tsukuyomi Komoe. Also a member of Anti-Skill, she cares for the well-being of children even if they are criminals, and absolutely believes that she will not use a weapon on children.

She is the current legal guardian of Accelerator, Last Order, and Misaka Worst.

Appearance
She is a tall woman that has glamorous proportions, and is always seen with a green jersey, which hugs tightly on her large bust. Her long hair is tied into a ponytail, making her look careless, but also gives her an intriguing sexy feeling.

Personality
She has a kind and caring nature, that extends to her job as Anti-Skill, and is most especially apparent with children, which she has promised to herself never to turn a weapon on them. However, her love more or less encompasses violence that an old generation P.E. teacher like her will execute.

She takes her job seriously, and often berates her junior, Tessou Tsuzuri if she doesn't do her job properly on patrols. Due to her habit of ramming delinquents with protective items like shield or helmets to resolve incidents, saying it's alright to do so since those are protective items, she's known as 'the woman who uses comedy-like methods to solve problems that could end up as a tragedy'.

Out of the job, she is very cheerful, and enjoys beer, eatouts, and public baths with her friends, apparently, willing to go become pass-out drunk in public. She also enjoys teasing Tsukuyomi Komoe as if she was a child. She also believes that there is no shame in showing her naked body to teenagers like Accelerator since they are still children. This was shown when he walked in on her, Last Order and Yoshikawa Kikyou showering, they didn't feel embarrassed one bit and acted casual about it since they believed that he was still a child and that they were adults and it was okay. She also has a tendency of going on a cleaning spree when upset which ends up in making her do reckless things like losing her keys.

Background
Not much known about her past, but it has been shown that she is good friends with Yoshikawa Kikyou, to the point that she can ask Aiho to take care of two children for her, as well as take her in. It is implied that Aiho has done something terrible for her to warrant not to use a weapon at a child even if they were espers, but it is unknown what had happened.

She took the test to join Anti-Skill at the same time as the Tokiwadai Dorm Supervisor, but both ended up failing to complete the test by beating up all the instructors. While Yomikawa managed to pass by apologizing, the dorm supervisor gave up on joining, both due to being disappointed in the instructors and because she thought herself more suited to protect a single place she lives in instead of the entire city.

At some point before the series began, Aiho and her team dismantled the Special Ability Institute, the place where Accelerator was in until he was nine. Yomikawa Aiho lives in Family Side and is a teacher in A Certain High School, where she teaches a class full of elites, which is just next door to Komoe's class.

Kazakiri Hyouka Arc
She is first seen telling Touma to keep safe while he withdraws his money. She is later formally introduced as a teacher in A Certain High School, talking to Tsukuyomi Komoe about Kamijou Touma's secret meeting with outsiders (Index and Kazakiri Hyouka), and later asks Komoe to confirm if there were actually two outsiders. She later leaves as she receives a call to capture an intruder in Academy City, Sherry Cromwell.

She reappears doing battle with Sherry's golem, to which their meager weapons cannot hold a candle to it. They are later decimated by a grenade that accidentally exploded near them, though injured, they all survived. As she comes to, she discovers Touma approaching, and knows that he is one Komoe's students, she and some of her group try to stop him, but she is too injured to do anything. In the original novel, the battle continues for longer, to the point where Hyouka appears wondering about Touma, as she is hit by a deflected bullet that utterly blows off half of her face. This event leads to her discovering that she is not human.

Later, after Touma discovers that he alone is not enough to beat the golem inside the School District 7 Underground Shopping Center and save Hyouka, she asks Aiho and the Anti-Skill help him save his friend. With that, they follow his plan. After Touma destroys the golem in order to save Hyouka. Sherry creates another one, at which point, Aiho protects Touma and Hyouka from any bullets and debris that might hit them. She orders her unit to fire at the golem in full force, to prevent Sherry from making any dangerous movements, lest she gets hits by the bullets. The battle draws out, Aiho asks Touma if he is going to continue with his plan, telling him that nobody will blame him if he chickens out. However, Touma is determined in going through with his plan. Aiho then orders the stopping in firing to allow to charge forward. Here, Aiho, though nervous of the great danger Touma puts himself through, and with some trouble, sees that he actually pulls through his plan. She once again tells her unit to fire, trapping Touma and Sherry behind the golem. Without anywhere to go, Touma successfully punches Sherry, stopping the golem. Sherry later gets away by going further underground with her magic.

Touma later demands Aiho to remove the barriers preventing their escape from the Underground Mall, as Sherry has turned her eyes Index, however, Aiho says that it is beyond their power. Touma is later taken into Anti-Skill custody during the end of the arc for all the trouble he caused them, which is assumed to be Aiho's group.

Tree Diagram Remnant Arc
She is briefly seen guarding the bathroom that Accelerator and Last Order are using to bathing in, complaining about Kikyou giving her such a job, as she recuperates from her run-in with Amai Ao.

She and her unit is later tasked to attack the Science Association that is outside of Academy City, who has tasked Musujime Awaki to retrieve the Remnant of Tree Diagram. Awaki hears the battle ensue right after overcoming Shirai Kuroko,and falls into despair after they are overwhelmed.

Daihasei Festival Arc
As a member of Anti-Skill, she is to keep the peace while the festivities go on. She meets Touma and Index when she blocks their way from crossing the street. She tells them that they would have to take the long route in order to get across, much to Index's dismay.

She later accompanies Tsukuyomi Komoe during lunch time.

Academy City Invasion Arc
Before the start of the invasion, Aiho is first referenced by Kikyou to Accelerator and Last Order as the one who will be taking care of them from now on. Aiho is first seen talking to Komoe about her preference: alcohol or tobacco. Komoe, however, states that alcohol is prohibited during work, to which Aiho decides that they should smoke. After discussing the state of Academy City's economy, Aiho then invites Komoe to join her into meeting the new students of the school. Accelerator and Last Order later arrives at A Certain High School, to which he and Last Order are introduced to Komoe. Accelerator then expresses his shock at Komoe's petite figure, then assumes that she is part of an experiment that involves stopping cellular aging. Komoe protests at his idea of her as a guinea pig, and soon, Aiho invites them to her car to take them to her apartment. There, Accelerator wants to confirm if Aiho is determined to take them into custody, considering his contact with the dark side of Academy City. Aiho proudly tells him that her job will keep her safe at best. Accelerator continues to point out the risks of taking him in, but Aiho smiles and instead, pertains what he has been blurting out as his declaration that he will protect them, much to the Level 5's annoyance.

As they arrive at her aparment, Aiho reassures Accelerator of their safety from any potential attacks. Aiho later argues with Kikyou in regards with her habits, as they leave Accelerator and Last Order to their own devices. She, Kikyou, and Last Order, later take a bath together, and as they dry themselves, Accelerator enters, much to Last Order's surprise and embarrassment. Aiho and Kikyou takes this event cooly, apologizing for not locking as she has been living alone for so long, which Kikyou calls her an idiot and tells her to "cover them [her breasts] up". Last Order asks why they are not causing an uproar, to which Aiho says that it's because Accelerator is just a kid while they are adults. Aiho and Kikyou later punish Last Order for insinuating they were old women. After Accelerator realizes that Last Order is missing, and discovers that she went out despite the apparent danger of her going out, she and Yoshikawa prevent him from destroying her phone. Aiho later suggests that she will help Accelerator with searching for Last Order using Anti-Skill technology, as finding lost children is still part of her duty.

Accelerator manages to track down Last Order's last known location, thanks to Aiho's help. As they talk by phone, Aiho decides to ask Accelerator an important question: "Is showing goodwill to others really that scary?" Accelerator does not seem to understand what Aiho tries to point out at first, but soon, Aiho clarifies things; she thinks that Accelerator is still fearful of returning his goodwill he receives from Last Order. Aiho then recalls on his past, as part of the experiments of the Special Ability Holders Multiple Alteration Technologies Research Institute. He has accepted that fact that he was a monster since his days in the said facility, and because of this, he thinks that he is no longer able to show goodwill to people. Nonetheless, Aiho believes that Accelerator will have the potential of helping others through his powers. Accelerator momentarily thinks of what should have happened when he had used his ability to stop the experiment, but he does not have the courage to think aloud.

During Vento of the Front's invasion, Aiho begins to wonder why there are no cars in the streets. In her car, she receives a photograph of Vento of the Front, and requests details from headquarters but could not get any. After taking a look at the photograph of Vento of the Front, she collapses due to the effects of Vento of the Front's Divine Punishment. She is later found by Kikyou who is unsuccessful in waking her up. After Touma defeats Vento of the Front, Aiho was eventually freed from the "Divine Punishment's" curse.

Skill-Out Uprising
In the aftermath of the invasion, she states that Accelerator "left her home", however unbeknownst to her, this was so because Accelerator was forced to join GROUP. She is first seen talking to Komoe about Nagatenjouki Academy trying to implement the Power Curriculum Program on a cat, and later talks about Komoe's runaway girls. Their conversation ends as Komoe hears a ruckus in her class. Her duties as an Anti-Skill have increased due to the need to increase security for the impending war. However, she also states that while they have increased security at Academy City's borders, this has also caused the Skill-Out to become more ambitious in their own goals.

During the Index II finale, she is seen having a conversation with Kikyou and Komoe, complaining that she was requested for additional work as a representative of Anti-Skill.

Document of Constantine Arc
Aiho was forced to perform a power suit demonstration for investors, the Interceptor Show, in School District 3 at the start of the arc. Aiho noted how it was terribly uncomfortable to pilot a power suit while wearing an Anti-Skill bullet-proof armor vest to which the scientist monitoring the suit's operation answered that Yomikawa could have perfectly choose to pilot the suit wearing a bikini if she so desired. She later sees news on the recent anti-Academy City sentimets that are happening all around in Europe. She and the researcher later discuss the true nature of the of the exhibition, and shows anxiety regarding the recent events.

Battle Royale Arc
She is first seen conversing with Hamazura Shiage who was just about to break into a car, and becomes suspicious of him as he was near a particle engineering lab that was being demolished by ITEM during their fight with SCHOOL. Shiage later tricks Aiho that there is a baby trapped in the car he was about to steal, which made the car's alarm sound off as she tries to open it. As Shiage goes into the car with a hasty Mugino Shizuri and Takitsubo Rikou, Aiho yells out to him what the car he is driving all about, to which Shiage replies that he just got his license.

After the Shiage and Rikou's falling out with ITEM, Aiho meets up with them, where Shiage gives an unconscious Rikou to her. Shiage hastily explains that she has been using Ability Body Crystal, which is slowly killing her. At that moment, a bloodied Mugino appears before them, carrying the upper half of Frenda's corpse, whom she killed for her betrayal. Shiage pleads to Aiho to leave with Rikou as she has no way to take on Mugino, the 4th ranked Level 5. Aiho hesitates for a moment, but acquiesces and tells Shiage not to die, as she will bring a fully armed Anti-Skill team once she gets Rikou safe. After Shiage defeats Mugino, he later calls Aiho to inform her that the Anit-Skill is no longer needed.

She is reunited with Accelerator after she witnesses him defeating Kakine for the first time; she manages to convince Accelerator to let go of the gun and spare Kakine Teitoku, but she is stabbed by Dark Matter which infuriates Accelerator. Aiho's body is stepped on by Kakine with his Dark Matter, to make fun of Accelerator, which pushes him to the edge. Luckily, Aiho was able to survive, and tries to stop Accelerator after she comes to. However, she is stopped by Saigou Ryouta, who tells a great distortion is taking place with regards to the AIM Diffusion Fields. She breaks from Ryouta's grasp, only to discover several armored Anti-Skills and armored vehicles. Aiho demands them to put their guns down, and tells that it is their duty to protect Accelerator. Aiho tries to come close to Accelerator, though because she is injured, blood spurts from her mouth, and is restrained by Ryouta. Aiho later witnesses Last Order approaching Accelerator, however, Anti-Skill begins firing on him without permission. However, despite this, Last Order is able to stave off Accelerator's wrath, and he calms down.

Acqua of the Back Arc
She is in the faculty room as Komoe's class begins to starve due to lack of lunch. Here, as Touma pleads his case to open the culinary classroom, she is shown eating a large meat bun as the amount of calories that she burns is unrelated to the amount of rice that she intakes, and along with the lunch of her fellow teachers, has Touma leaving with in irritation.

British Royal Family Arc
Aiho is in a restaurant, among other large breasted girls, as Misaka Mikoto observes her during the height of the British Halloween in the United Kingdom, lamenting the fact that Aiho and the others have large breasts.

DRAGON Arc
Accelerator broke into her apartment and took Last Order away with him and left her a note. Afterwards, Accelerator broke his only link to her as well as any other people in his life by destroying his phone. Here, she discovers a note from Accelerator, promising that he will definitely save Last Order.

Freshmen Arc
When Accelerator came back from Russia, it was said that she punched him and then hugged him. She also tried to stop an argument between Last Order and Kikyou over a breast enlarging device, but somehow ended up getting involved herself.

Ichihanaran Festival Arc
During the last day of the preparations for the Ichihanaransai, Kikyou mentions that Aiho is out patrolling the streets. She is dispatched during the Red Code alert status in Academy City after Fräulein Kreutune escaped the Windowless Building due to the efforts of Touma and Thor.

She reappears a bit away from away from the Windowless Building after the hole on its wall has been covered. She is surprised that Kakita and Momozawa's teams have been taken out, and later tells her subordinates not to let their guard down with Fräulein has they have no idea what Fräulein could do.

During the festival, Yomikawa Aiho contacts fellow Anti-Skill colleagues, Sumomo, Hakutou, and Kurumi, regarding the strange information blackout regarding Fräulein. Aiho later plans on taking Kurumi, and tells both Sumomo and Hakutou to go back to the station to secure paper reports if possible, if not, then retrieve the temporary cache from the copier. Sumomo warns though, that whoever is blocking information is most likely a step ahead of them.

Agitate Halation Arc
Yomikawa Aiho is called into School District 23 as her services are needed there despite her jurisdiction is only in School District 7, where she is to capture Dr. Matsusada alive after he tries to illegally leave the city due to the effects of the Agitate Halation Project. She partners up with Stephanie Gorgeouspalace who was just released prison. Aiho is mostly spends time on the sidelines as Stephanie barges in the room where Matsusada is hiding with her gatling guns outfitted on Security robots, and assuring her that she will not kill him.

After cornering him, Matsusada says that they do not understand what's going on, and accuses them of being affected by Agitate Halation already. He tries to tell them of his fearful situation, but he apparently used the hibernation drug cp-191 on his person, making lose consciousness. He is later take to ICU, while Aiho waits on him, she reads Matsusada's The Future of Next-Generation Processors using Viscosity and Density, though does not understand its implications. She later leaves knowing that Matsusada will not wake.

Magic God Invasion Arc
Aiho is with Kikyou in a subway station during the High Priest's rampage. Kikyou assumes that Aiho is going home but she tells her that she is trying to start up an investigation after her colleague Shiosai, got his P-Phone and handgun stolen by someone. Hearing Aiho getting pulled around by her job makes Kikyou consider getting a real job, though she says that she'll just keep volunteering for the meantime, much to Aiho's chagrin.

Akikawa Mie nearly runs into them during her flight to take the Liquid Diamond to her mother, much to their confusion.

Processor Suit Arc
She was present at District 7 Central Anti-Skill Station when it was attacked by A. O. Francisca and the Mimetic Predators. Injured during the attack, she was treated by Hamazura Shiage, who was wearing a Processor Suit. Recognizing that they couldn't contain the attacker, she told him where the baby Lilith was and gave him a key to the storeroom on the way to the nursery to buy him some time.

Coronzon Arc
During the evacuation of Academy City on December 12th, Yomikawa assisted in coordinating evacuation.

Christmas Eve Arc
On December 24th, Yomikawa met with Accelerator, now Board Chairman, in a windowless room of a certain Anti-Skill station, and discussed the imminent Operation Handcuffs - his plan to eliminate the Dark Side of Academy City.

After Maidono Hoshimi's attempt to kidnap Last Order was thwarted and Misaka 10032 brought evidence of Director Neoka Norito's involvement to them, with the two reaching the safety of the Anti-Skill station, Yomikawa removed her formal suit and left for the subsequent deployment.

Toaru Kagaku no Railgun
Aiho only does a cameo in the original Toaru Kagaku no Railgun manga's first chapter, but her role is expanded upon and replaces several unnamed characters in the anime adaptation.

Level Upper Arc
She is retconned into the arc in the Toaru Kagaku no Railgun anime. Here, she first appears alongside her partner, Tessou Tsuzuri after Okahara Ryouta's attempted bank robbery, taking them into custody. She later appears prominently after Kiyama Harumi is discovered to be the master mind of the Level Upper. She along with Tsuzuri, are part of the team to capture Harumi and retrieve Uiharu Kazari (after being kidnapped by Harumi). They later engage a battle against Harumi, using Multi-Skill, a side-effect of the Level Upper Network, and is completely overwhelmed by her. She later aids Misaka Mikoto and Uiharu Kazari in their plan to stop the AIM Burst that have appeared after Mikoto defeated Harumi. Aiho and the others later take Harumi into custody after the incident.

She reappears later during the special class for the Level Upper users as the P.E. teacher. Here, she has them run around a track, and tells them to go beyond the limits of their abilities. She forces Saten Ruiko to keep on running even after she raised her hand that she couldn't do it anymore. She later takes Elder Sister down, who attacks her, after complaining about their treatment. She then uses Koujun Kikuhiko as an example of someone who doesn't give up despite raising his hand that he couldn't run anymore. Due to rain, she tells them to go back inside. She later appears with Tsukuyomi Komoe after her lecture regarding Personal Reality for their System Scan.

Poltergeist Arc
She first appears in the arc as being partner's with Tessou Tsuzuri on patrol. She saves Tsuzuri from a thug with one of her famous "comedy-like methods to solve problems that could end up as a tragedy." She berates Tsuzuri for her performance, and later tells her to make it up for it by telling, Misaka Mikoto, Shirai Kuroko, Uiharu Kazari, and Saten Ruiko to go home because curfew is near. She later slaps Tsuzuri at the back of the head for getting led on by the kids, and tells the group to go home, as well as the taciturn Kounoe Haruki. She later goes to a public bath with Tsuzuri and Komoe, and lectures the former again about her performance. They later go out to eat, to which a drunken Aiho tells Tsuzuri to make an impact. The next day, Aiho tells Tsuzuri's duties for the day, which goes awfully. During their bath together again, Aiho begins to notice Tsuzuri's depressed state, and as they eat out again, a tipsy Aiho asks her what's wrong, and tells her to do what she likes doing in order to relax. Aiho is forced to go on patrol the next day, as Tessou has failed to keep up with her work as a teacher. Aiho later becomes too drunk, and is later carried by Tsuzuri home. Aiho, the next day, doesn't get a hang over, and with Tsuzuri. She is later surpised by her enthusiasm. Aiho later calls Tsuzuri, worried about her, and tells her to come to their usual eating spot to treat her and Komoe. She is later present with Tsuzuri when Ruiko and Kazari tells her that Haruki has moved to a videogame development school, and notices her joy. With that, Aiho reminds the girls to go home before curfew, and is surprised by Tsuzuri's high spirits as they ready for another round of patrolling.

She and Tsuzuri are later chosen to guard Tokiwadai Middle School's Midsummer festival. She later chastises Tsuzuri for eating too much from the buffet, and later guards her while listening to Mikoto's violin solo.

Finally, during the height of the RSPK Syndrome earthquakes, she is chosen as the presenter in the coalition meeting between Anti-Skill and Judgment. She later introduces guess speaker Therestina of MAR regarding the earthquakes. She reappears, dejected after MAR contacted them they need not worry about the Poltergeist earthquakes anymore, however, she becomes suspicious because MAR will not reveal any details. She is later called by Judgment 177 Branch Office, regarding the true nature of the MAR and Therestina, to which Aiho replies that they can do little because they have limits as well. It is not until Ruiko talks to her, that acquiesces to their demands. As Therestina chases Kiyama Harumi, Misaka Mikoto, Uiharu Kazari, and Saten Ruiko, in Harumi's car, she and her Anti-Skill unit distract and bother an MAR unit, foiling Therestina's plans on having the car intercepted by them. After the end of the arc, she and Tsuzuri look up to the sky to look at the blimp that contained Harumi's student's message to her.

Silent Party Arc
She is first seen in the venue for the Academy City Research Exhibition Assembly for the preparations where she notices two Judgment members talking to a deliveryman about some deliveries (actually Powered Suits from STUDY) for the assembly except the receiver not being present. She later cooperates with Konori Mii, Shirai Kuroko, and Uiharu Kazari of Judgment regarding the runaway Security robots that attacked Febrie. One of her colleagues notes on how the robots did not move without any batteries. She later meets the girls again after a similar circumstance occur again with Febrie who was attacked by a Powered Suit without a pilot. As she investigates the scene, she discovers a mysterious filament inside the Powered Suit.

Aiho's actions are essentially neutered and kept in check throughout the entire arc as STUDY Corporation a medical manufacturer who supplies Anti-Skill with tools extends their influence over the force. Because of this, her discovery of the mysterious filament inside the Powered Suit that attack Febrie is unused in their investigation due to the pressures of her superiors. She later passes the valuable evidence down to the kids, Misaka Mikoto and Shirai Kuroko as they make their own investigation as Anti-Skill is incapable of helping them.

Her meddling later gets her into trouble and is suspended. As she stays with Komoe, she gets a call from Kuroko referring to STUDY's true nature. Here, she informs them of STUDY's influence on the organization and how she was suspended. She is somehow later tasked to deliver the Ekaterina II S, to the frontlines of the battle against STUDY, where many members of Judgment are fighting against armed and dangerous Powered Suits controlled by Diffusion Ghost. Somehow, she picks up Haruue Erii along the way, and later slams the thing on Kosako Shunichi and Madarame Kenji's mobile weapons that are attacking Judgment members. She then gives the truck that transforms into a mecha into the hands of Ruiko and Kazari and disappears from the story. It is unknown where Aiho went to after delivering the mecha.

She briefly reappears on September 2, while looking at the sky with Tsuzuri next to her.

Dream Ranker Arc
She made a brief appearance in Yoshikawa Kikyou's dream (experienced by Misaka Mikoto through Indian Poker), where Yoshikawa compared herself (who had measured no bust growth since her teens) to her and wondered if her breasts were her true form.

The proliferation of Indian Poker led to information previously restricted to School Garden leaking outside, with the nature of the card's production complicating the schools' efforts to prevent information leaks. After toys used to make the card dispenser were recalled by their manufacturers, likely under pressure from School Garden, an alternative design using different toys was uploaded. Yomikawa and Tessou were among the Anti-Skill members attempting to find the uploader, without success.

Toaru Kagaku no Accelerator
Yomikawa's team responded to a break-in at the Atmospheric Continuum Mechanics Research Facility, with Yomikawa wondering what they could be after given the facility's apparent purpose, arriving too late to stop the thieves who cut through the floor and escaping underground. Later that day, having learnt that the stolen equipment was a weapon intended for use against Accelerator, Yomikawa's team went to Heaven Canceller's Hospital where Accelerator was being treated after being shot in the head, as that was where the thieves were likely to strike next. They subsequently fought the trio of thieves when they came looking for Accelerator, hoping to obtain a sample of his genetic information.

Necromancer Arc
Yomikawa met with Accelerator after his battle with the Prototype Coffin outside Heaven Canceller's Hospital. Learning about the group posing as Anti-Skill and their ability-using weapon, Yomikawa confirmed that the corpse inside the Coffin was that of Hitokawa Hasami, who had apparently committed suicide several days prior by jumping off a bridge into a river but whose body was never found, as well as the fact that she was a Level 2, with both Yomikawa and Accelerator noting the discrepancy with the Level 4-class damage which had been caused by the Coffin.

After another incident at the hospital, Yomikawa carried out an investigation into DA and found a large amount of files on the organization which had not been accessible before (with the high-level backer who had previously kept them from Anti-Skill having withdrawn his support), detailing its equipment and personnel. Recognizing many disgraced Anti-Skill members among the line-up, Yomikawa thought that it was as if the darkness of Anti-Skill had gathered in one place. She was then alerted to an explosion at School District 3's warehouse area, one of the locations used by DA.

Yomikawa was among the Anti-Skill teams sent to crush DA. During the battle, she noticed several DA members trying to escape with a black bag. With assistance from her colleague, Yomikawa leapt up to intercept them and was enraged at seeing signs that the bag contained a person. During the subsequent struggle, she was shocked to learn that the bag contained a girl who looked like Misaka Mikoto. She also witnessed the carnage wrought by the Tarantula and the arrival of Scavenger. The damage from the clash between the two caused the level Yomikawa was on to partially collapse. She unsuccessfully attempted to prevent the Sister from falling but Esther Rosenthal and Huotou arrived in time to save her. Though surprised at seeing the late Hitokawa Hasami up and about, she stood with the two to protect Misaka 10046 from Scavenger, who were keen to kill a teacher such as herself, but was knocked out early on in the battle.

In the manga, Yomikawa regained consciousness as the wounded from the battle were being treated, with initial first aid having been carried out by Esther, who had departed after letting the reinforcements know their whereabouts but before their arrival. In the anime, she and Misaka 10046 regained consciousness shortly before the arrival of the Coffins and the latter's abduction. After contacting her colleagues, she received a brief explanation from Esther about Hitokawa Hasami's current state, the necromancy being used with her and in the Coffins made by Hishigata Mikihiko, and the danger posed by the Evil Spirits of the Numbers, before Esther and Huotou left to help resolve the incident. She was subsequently involved in the battle against the remaining members of DA at Seiin High School and witnessed the events which unfolded there.

After the incident's conclusion, Yomikawa visited Accelerator in hospital, hoping to learn more about what had transpired since he was there. When she arrived, she passed Last Order as she went out on an apparent errand, briefly wondering about her but not saying anything. She apologized to Accelerator for the trouble that they had caused him, adding that he did rid Anti-Skill of some scum, before asking him about the incident. She was not particularly satisfied with Accelerator's answer, but with Last Order having run back and making a fuss after realizing she had been fooled, Yomikawa decided it would be better to come back some other time and left, taking Last Order with her.

Nectar Arc
Last Order visited Yomikawa at work to inquire about Himegi Matsuri after she apparently disappeared after leaving the hospital with a group from Anti-Skill a couple of days previously. Although initially reluctant to divulge information due to the risk of someone listening in, having dragged Last Order into a private room when she first said the name, she eventually told Last Order that Himegi was a person of interest in a case and was being pursued by an organization from the Dark Side of Academy City, confirming her safety but not allowing Last Order to see her.

Following Himegi Matsuri's abduction by Full Course, Yomikawa questioned the injured Tobio Yumi, learning about the circumstances surrounding her sibling Tobio Mami, who had disappeared after an apparent abduction under the pretext of treatment for her illness but resurfaced in Full Course's service. Learning that a member of the Board of Directors was involved in the case, Yomikawa decided to secretly take action on her own, managing to get aboard the Escoffier and encountering Accelerator again along the way.

The Third Friday of January
Yomikawa Aiho, whose vehicle was used as part of the barricade, manages to jump out of the way as Shiage, Ritoku, and Hanzou manage to get away with their stolen ATM after smashing through the barricade. Their recklessness makes Aiho interested of them. As they drive off and try to get as far away as possible, they find Yomikawa Aiho uses a Fukuoka Fireworks Manufacturing large specialized transport truck catch up to them from a side street, slamming into the station wagon. Shiage lets their station wagon slide as so not to lose control. After he regains control of the vehicle he speeds off again. They later see that she has passed off the vehicle as an Anti-Skill vehicle by attaching red lights on top and uses a megaphone to ordering them to stop.

Hanzou tries to shoot at her, but she uses the truck to pin the station wagon on a guard rail. As it could not handle the force, the rail breaks apart with the station wagon and transport vehicle, sending them into an uninhabited warehouse. After striking the inner wall of the warehouse, the truck becomes stuck and couldn't move anymore. Aiho is later given a three-shot at by Hanzou, who says that it is powerful and cool to fire a bunch of bullets at once. Hearing their argument, Aiho determines that her opponents are all idiots. Suddenly, either due to the crash, the gunshots, or both, the truck's transport of soccer ball-sized fireworks falls out all over the warehouse. Moreover, Hanzou's haphazard firing had hit some sort of electrical wire which in turn has come into contact with some leaking gasoline from the truck. Seeing this, Aiho flees.

This was apparently all set-up by Shiage, who had Hanzou fire at the truck's fuel tank. The three then find that Aiho is running away, to which Shiage says that he wants to capture her and show her up. Ritoku responds that they will do no sexual crimes, though Shiage says he knows and changes the subject to the ATM. As Shiage tries to go back to the station wagon, something hit his toes. Much to their horror, they find one of the soccer ball-sized fireworks spheres on the ground and that the truck they hit is from Fukuoka Fireworks Manufacturing. With a flash from the electric wires that has been severed, the fireworks explode. Aiho later comes and arrest the three after escaping the explosion.

The Second Friday of June
Aiho is apparently with Uiharu Kazari in an open café. Being too lazy to submit her report to school in person, she asks a waitress if there is a wireless LAN in the establishment as she wants to send it through the Internet instead. Her willingness to use an use the wireless LAN without countermeasures earns the contempt of Kuyama Kihan, calling her an amateur for being a casual user of computers.

She is working on her report while Kazari, the Goalkeeper, is challenged by Kihan in the same establishment. It is unknown what Aiho did afterwards, but it is likely she bears witness to Kihan being apprehended by Anti-Skill after Kazari reports his location. She is likely left behind as she works on her report after Kazari leaves.

Toaru Majutsu no Index: Love Letter Competition
Aiho is with Komoe after Fukiyose Seiri charged the latter with giving Touma the Kumokawa Seria's "love letter" to him. Aiho makes fun of Komoe for not being able to drink, and then notes on how Komoe seems not want to deliver the letter. When the wind blows the letter away, Aiho and Komoe try to go after it, but loses it as it comes near Misaka Mikoto who has been eavesdropping on their conversation.

Toaru Majutsu no Index Movie: Miracle of Endymion
Aiho appears as a leader of a squad of Anti-Skill after discovering that the Endymion has been mysteriously sealed. She orders the attack on a large mobile weapon that guards one of the entrances, and are only able to get through after Mikoto and Kuroko arrives to destroy it.

Later, she commands the Anti-Skill from the outside, and after hearing that Endymion is in danger of collapse and that they need to destroy the explosive bolts to force the space elevator to break away from the earth, she and a few of her men offer to take one down. Underground however, they are forced to face strong opposition from countless mobile weapons. Here, she apologizes for failing, but then overhears from the network Misaka Imouto intending to help. In the end, it is Accelerator that destroys their explosive bolt for them.

Toaru Majutsu no Index-tan
Aiho only appears in the fourth episode of the shorts. Here, she accompanies Komoe, then suddenly hears a ruckus coming from her class, which shocks Komoe. After entering, the students ask what kind of bra she wears, back or front. Komoe replies that she doesn't wear one because she wears a training bra. As Komoe assesses the situation inside, Aiho remarks that she is somewhat jealous of Komoe's class, who is able to enjoy things without any worries.

Toaru Kagaku no Railgun MMR: Much More Railgun
Aiho appears in the first episode with Tsuzuri and Komoe, eating a deluxe dinner set. Aiho tells Tsuzuri that she is not allowed to eat meat since she causes a lot of trouble. Komoe notes that Aiho likes to use "jan" for some reason. To which Aiho references several things that sound like jan, from to  of .

Abilities
As a member of Anti-Skill, she is trained in basic combat training, being able to take down thugs unarmed, as well as capable of using various firearms. She also knows how to operate Powered Suits. However, her greatest attribute is her ability to use "comedy-like methods to solve problems that could end up as a tragedy," using shields or other non-weapon objects to take down rampaging espers.

Design Evolution
Aiho's design has remained static throughout all her appearances in the series. Just like Sherry Cromwell, Haimura designed her differently than the standard moe character fare.

Quotes

 * (To Accelerator in Index II Episode 17) "Just listen to yourself. Despite all you're saying, you're trying to point out the risks your guardian is taking. That means you are ready to protect us."
 * (To Accelerator in Index II Episode 18) "This is a rule I made for myself: I will never point a weapon at a child. Even if they're an esper. Do you know why?... That's exactly it. It's probably nothing compared to what you have to face. But the fact that we're heavily indebted to others is the same. So no matter how painful it is, there's no choice but to pay back as much as possible. And unlike me, if you have strength. There are many doors open to you."
 * (To Elder Sister in Railgun Episode 14) "How about surpassing your limits? Look at that guy. He was the first to raise his hand, but he's still running. The instant you say you're done and give up, it's over. You might have power in you that you aren't aware of yet. And her. She thought she was done too, but she ran another lap. Where did the power to run that lap come from? It's the same with ability development. If you decide your own limits yourself, it's over."
 * (To Accelerator in Index Volume 15) "It doesn’t matter whether you are a Villain or Hero, Accelerator, nor is what kind of world that you are involved in. For me, what’s most important is bringing you back. No matter how dark or cold your world is, I’ll never give you up, and drag you back!"
 * (To Anti-Skills regarding Accelerator in Index Volume 15) "'Do you know who it is standing there?! That is a child that we must protect! Pointing guns at children, I’ll never agree! How could I possibly agree to something like this!!” -- Said in Vol15 to prevent Anti-Skills attacking Accelerator.
 * (To Hamazura Shiage, Komaba Ritoku, and Hattori Hanzou in Index Volume SS2) "U-umm.. This is Yomikawa Aiho of Anti-Skill Branch 73. With charges of theft, property damage, attempted murder, and interference with a public servant's duties, I'm taking you pieces of shit down to Hell!!"