Saten Ruiko

Saten Ruiko (佐天 涙子) is a character from the Toaru Kagaku no Railgun sidestories. She is voiced by Kanae Ito. She is a Level 0 Academy City student and is a classmate and close friend of Uiharu Kazari.

Appearance
Saten Ruiko is a girl with blue eyes and long black hair with a small, white flower on the left side of her hair. She also prefers wearing medium-sized skirts instead of short ones.

Personality
She has an outgoing and friendly personality, but is a little shameless as she sometimes flips Kazari's (and only her's) skirt in public. At first, she displayed apathy towards being a Level 0 but then became envious of the abilities of her friends as she was unable to fulfill her dreams as an esper. Due to this, she used the Level Upper. Later on, she grows to accept herself and becomes determined to develop her own abilities. Like her friend Kazari, she also has a deep sense of friendship; she was instrumental in helping Kazari and Kuroko make amends and made Mikoto realize that she has friends who she can count on. Not only that, but she is adept at reading the atmosphere, and often changes the topic when someone is feeling uncomfortable about something.

She is superstitious despite being in the city of science, though she likes to presume otherwise as when she states that she doesn't believe that her mother's good luck charm actually works. Because of this, she is a fan of internet rumors and urban legends, and loves telling her friends about them. This extends to herself, believing that her nose is sensitive to money, though she backs this up by showing Mikoto four bank cards she had already obtained. She has a natural tendency to be nosy regarding this, and often gets herself into trouble because of it, often needing to be saved by coincidental events or having become involved in events.

Saten Ruiko can be described as a normal-acting preteen in the series in comparison to her peers, not having any extracurricular activities like Judgment or being particularly book smart. She is very affable, quick to make friends, and cheerful. She knows the latest trends and fashions, and in fact has the most wardrobe changes in the series.

Background
She was born outside Academy City and when she was younger, she decided that she wanted to go to Academy City to become an esper. She even boasted to her brother that she was going to get powers. Her mother, although disapproving of her decision as she was afraid of what the city would do to her head, supported her regardless and said she could come back anytime. Her mother also gave her a good luck charm, which is shown to be always attached to her bag.

Sometime in Academy City, she became close friends with Uiharu Kazari. She eventually enrolled into Sakugawa Middle School along with Kazari and was classified as a Level 0. She also let down her hair and wore a white flower on the left side of her head. She is currently a 1st year student in class 1-D.

Toaru Majutsu no Index
Although she doesn't appear in the actual show, both her and Kazari appear in the first and second openings, PSI-Missing and Masterpiece respectively. In the first opening, they can both be seen sitting in a café with Kuroko with their backs facing the camera. In the second opening, they walk by in front of Mikoto before the camera flashes to her.

Magic God Othinus Arc
In the final recreation of the world by Othinus created specifically to break Touma's spirit, known as the Version_Omega world in-text, where several characters from the original world have been "saved" or have not experienced great tragedy, Kuroko, Kazari, and Ruiko are in the festival where Touma is after his spirit has already been broken, trying to decide how he should have himself killed. Here, they are all aware of the existence of clones. Kuroko complains on how there are too many people in the festival and wonders where Mikoto had ran off to. Kazari comments on how it would be impossible to find her in the festival with all the people who look like her. Ruiko then comments on how she just remembered that Meigo Arisa may be coming in secret, referring to her "perfect mode" after becoming one with Shutaura Sequenzia. Kazari comments on how she saw the doll-like child president wandering around earlier, as such Arisa may be around.

Level Upper Arc

 * Main article: Level Upper Arc

Unlike the manga, Ruiko has a much more prominent role in the anime series.

She meets Mikoto earlier and in the first episode, she doubts the personality of Mikoto as she was a Level 5, supposedly an arrogant and snobbish type. However, an incident occurs involving young children and she does her best to aid Mikoto and the others despite having no abilities at all which, impresses Mikoto.

In a later episode, she also gains the affection of Jufuku Miho a Level Upper user after she said as a passing remark that she liked her eyebrows during her visit to the School Garden, in which she was attacked by her for wearing a Tokiwadai uniform.

Later, she becomes envious by the fact that every one of her friends had some sort of ability and is then curious about the Level Upper. After obtaining it, she becomes alienated by Mikoto's words saying that levels and abilities were not important. To Ruiko, wanting to gain abilities was the reason why she went to Academy City. She finally uses the Level Upper after being caught helpless when trying to save Koujun Kikuhiko from Trick's gang and then witnesses the battle between Kuroko and Trick, where Kuroko obtained injuries but is nevertheless successful and obtaining the source of Level Upper. She invites Makochin, Akemi, and Muu-chan to use the Level Upper and Ruiko seems to display powers over the wind; however, they were all soon struck by the side-effect of using the Level Upper, becoming comatose. She later goes back to her dorm and calls Kazari that she had Level Upper and had used it along with her friends. Blaming herself for what had happened, Ruiko is tearfully told by Kazari that everything was going to be alright and that she would be there to wake Ruiko up. She goes on to say Ruiko would always be Ruiko to her regardless of her abilities. This makes Ruiko feel better, but when Kazari arrived at her dormitory, Ruiko had already become unconscious. She was later taken to the hospital by Kazari.

After the defeat of Kiyama Harumi and the AIM Burst creature, she wakes up from her coma and is greeted by Kazari on the rooftop of the hospital. Ruiko apologizes to Kazari and realized that she almost lost something much more precious to her than abilities. She then proceeded to lift Kazari's skirt once more and the quartet reunites again.

Since she was a user of the Level Upper, she has to take supplementary lessons at A Certain High School. There she meets their teacher, Tsukuyomi Komoe, who teaches them the importance of having a Personal Reality for ability development. There, she also once again meets with Jufuku Miho, who shows a noticeable amount of affection for her. During running laps, Ruiko pushes herself to keep on running despite wanting to stop earlier and manages to be one of the last ones still running. There, Elder Sister argues with Yomikawa Aiho stating that this was just simply punishment for using Level Upper. Aiho rebuffs her stating that this was training to surpass one's limits, citing Ruiko and another runner as examples. She tells them that the development of abilities is akin in surpassing one's own limits. After going inside because of rain, Ruiko confronts Elder Sister on her views on why this was like punishment and says that it was only natural for them to be punished because they were cheating (using Level Upper) in achieving abilities, which her friends agreed on.

Near the end of the lessons, after taking in what Komoe said about achieving one's own Personal Reality and surpassing one's own limit, the Level Upper users were tested on how far their abilities had gone. After having witnessed Ruiko's confrontation with Elder Sister, Jufuku Miho decides to follow her example and live strongly like her from now on. Although Ruiko remains a Level 0, she is determined to keep on trying.

Big Spider Arc

 * Main article: Big Spider Arc

She first appears in a cafe along with Mikoto, Kuroko, and Kazari where they talk about the recent attacks on espers by Big Spider. Mikoto discusses how she does not like people who give up easily, which Ruiko tells her that she seems to be describing her. She later appears with Kazari eating together, talking about how she understands the feelings of Skill-Outs and reassures Kazari that she would never give up again.

After hearing about Kurozuma Wataru's and Konori Mii's confrontation, she becomes curious of their past. She later visit Konori Mii's apartment along with Mikoto, Kuroko, and Kazari, where Yanagisako Aomi, who is Mii's roommate, tells them that Mii was previously a member of Big Spider, much to her and everyone else's surprise. After leaving, she replies to Mikoto's statement about Mii, where Ruiko tells her that Mikoto should not look at people's past as simply what makes them right now. She later stops and explains that she was not trying to contradict her after seeing the reactions of Mikoto, Kuroko, and Kazari.

Poltergeist Arc

 * Main article: Poltergeist Arc

During the Poltergeist Incidents that were occurring around the city, Ruiko befriends Kazari's new friend, Haruue Erii, and helps both Uiharu and Haruee in fixing their yukatas for an upcoming evening festival. During the festival, another Poltergeist incident occurs, though everyone is left unscathed, partially thanks to the help of Multi Active Rescue.

In later episodes, Kuroko and Kazari come to a disagreement on Haruee's involvement in the Poltergeist Incidents. Ruiko is often seen trying to calm down the situation.

After the group discovers Therestina's true identity, Ruiko forces both and Kazari and Kuroko to apologize to each other after treating each other badly the past few days. Ruiko also chastises Mikoto for not telling anyone where she went off to (the Advanced Education Department and a hospital) and reminds her that she was not alone. During the preparations in confronting Therestina, Ruiko equips herself with a metal baseball bat.

She joins Uiharu in guiding Kiyama Harumi in finding the Child Errors that were kidnapped by Therestina. When they arrive at the location, they realize Therestina had set-up a trap, Capacity Down. Ruiko, however, is unaffected by Therestina's Capacity Down because she is a Level 0. She later interprets Kazari's queries on Therestina about the location of the sound system that controlled the Capacity Down. Through the sound system, Ruiko tells Therestina to not to hurt her friends and then proceeded to destroy it with her baseball bat, allowing Mikoto to defeat Therestina. It is this heroic act that finally earns her Kuroko's respect, making her finally regard her as a close friend rather than a casual acquaintance.

She is last seen with Uiharu, Misaka and Kuroko being late for the special event held by Haruee Erii for Kiyama Harumi.

Sisters Arc

 * Main article: Sisters Arc

Having heard of rumors of someone dropping cash cards, Ruiko uses her "nose" to find them and invites Mikoto to join her. She later gives Mikoto her share of bank cards and leaves afterwards, stating that she would like to bring Kazari next time.

In a later day, Ruiko and Kazari meet up with Kuroko to discuss why Mikoto suddenly seemed preoccupied. Ruiko concludes that Mikoto has boy problems, which shocks Kuroko and makes Kazari blush. Their conversation is cut-off when they hear a vending machine alarm, which Kuroko goes to investigate.

Near the end of the arc, Ruiko is asked by Mikoto to help her bake cookies for Touma (after he told Mikoto that he likes homemade cookies). Here, Ruiko is relieved that Mikoto is back to her normal self again and teases Mikoto about a certain boy, much to Mikoto's embarrassment.

Silent Party Arc

 * Main article: Silent Party Arc

Although for the most part of the arc she is seen only as a caretaker of Febrie and keeps Kazari company in her apartment after Erii moved away, Ruiko's role is major in the anime-original arc. She is the one who concocted a plan to get Febrie and Mikoto closer as the former doesn't like her for some reason and the latter is trying to desperately to become friends with her. When Mikoto tells them of Febrie's involvement in the dark side of Academy City, imploring for their aid to save her, Ruiko and the others jump at the call. She is later tasked in finding a way to make more of the lollipops that keep Febrie alive and visits Heaven Canceller for that purpose, though the results are not well. She is later seen aiding Kuroko in breaking out Mikoto after she is caught by STUDY as a lookout.

After deciding to take on STUDY and the Silent Party without any help at all from Anti-Skill for the sake of Febrie and Janie, Febrie's sister, Ruiko decide to help the others. She is given the manual on how to pilot a Ekaterina II S along with Kazari by Kongou Mitsuko, and memorizes it in a single night while making rice balls with Febrie. She takes her bat and with Kazari, who takes control of Security robots guard an entrance to the Academy City Research Exhibition Assembly, where the rebellion of STUDY will take place using 20,000 Powered Suits controlled by Diffusion Ghost. They are later joined by a multitude of Judgment members. During the offensive, despite being an ordinary middleschooler without any training and experience in battle, she is able to dodge the attacks of the Powered Suits, and with the help of other Judgment members take them down. Later, Madarame Kenji and Kosako Shunichi of STUDY try to counterattack using their large mobile weapons. As they retreat Kazari trips but is soon saved by the arrival of Yomikawa Aiho bringing the Ekaterina II S, and knocking out their mobile machines. This apparently gave the girls enough time to pilot and transform it into an even larger mecha. Ruiko and Kazari's memorizing a manual in a single night proves useful as they are able to easily to take down the two mobile weapons.

Ruiko and Kazari are part of the little conference held after Mikoto defeats Aritomi Haruki, STUDY's leader, who has launched the AIM bomb. As the other girls deal with that, Ruiko arrives in the laboratory where they kept Janie, and after inquiring from Haruki, gets more of the lollipops for Febrie.Due to Haruki's use of the AIM bomb, Janie becomes part of the system that has now gone out of control, making any sort of connection impossible as it will kill her. Despite this, Shinobu still attempts to save Janie from the runaway system. And as she is not taking any outside input, she has Febrie's "strong emotions" to reach her, as they share the same biological base. A plan that Saten Ruiko says is pretty much the "power of love," much to Shinobu's embarrassment.

Her untested plan is successful, with a little help from the Sister clones, stating that Janie and Febrie are like sisters to them as well, giving the computers a boost to allow Febrie's emotions to reach Janie. She later awakens, and Febrie greets her a good morning. Ruiko urges Febrie to give to Shinobu her gift, and here with tears in her eyes, Shinobu accepts the riceball gift that Febrie made for her the other night. Here, Shinobu says to the two of them that she has a lot of things she wants for them to see.

As Janie and Febrie are in a Kongou airline runway, preparing to leave to the outside for body readjustments, Ruiko cries over Febrie leaving. Kazari tries to console her but also falls into tears. And thus, the fellowship, though bound by friendship and love, part ways.

Daihasei Festival Arc

 * Main article: Daihasei Festival Arc (Railgun)

Kuroko, Ruiko, and Kazari appear right before Mikoto's competition in the three-legged race with her partner Kongou Mitsuko. Ruiko tells Kazari of a substance known as Shadow Metal that is formed by the clashing of multiple espers, which can be sold for a large sum of money. Kuroko then appears right after, angry at Ruiko for spreading rumors again, to which forces her to distract and stay her anger by pointing out that Mikoto's competition is about to begin.

After their victory, Xochitl, in disguise, tries to operate the unique cellphone that is the same to the one that Shirai Kuroko uses. Confounded by the technology, Saten Ruiko overhears her and goes to her aid. However, seeing Ruiko, surprises Xochitl to the point of shouting. Ruiko seems to feel that they have met somewhere before (referring to the events of Liberal Arts City), but because of Xochitl she couldn't tell. Xochitl then says she must be seeing things as she looks like someone she knows, confusing Ruiko. Uiharu Kazari then calls out to Ruiko that they should now leave. Before that however, Ruiko focuses her gaze on her, and tells her that she feels like that they really have met before. Xochitl insists that she is just imagining things and that she made a mistake, to which Ruiko agrees and then leaves.

Mikoto, Kazari, and Ruiko would later meet up with Misaka Misuzu. Mikoto notes that her clothes are dirty and that changing them would be difficult for the next event, to which Ruiko says that Mikoto should ask someone to go in her place. This however makes Mikoto accidentally divulge on her little bet with Kamijou Touma, which entices Misuzu and later has both Kazari and Ruiko discuss the person who is "helping Mikoto a lot", much to her embarrassment.

As the day goes on, at lunch break, Saten Ruiko is still up on about with Shadow Metal despite Kuroko's warning on not spreading the rumor, and manages to convince Uiharu Kazari to aid her in finding it. Ruiko then goes to Kirigaoka Girls' Academy grounds in School District 18. With no event there scheduled, Ruiko is able to search all she wants with Kazari's help who is constant communication with her from Judgment 177 Branch Office. Searching for information about Shadow Metal on the Internet, Kazari notes on how there is an unusually high amount of hits, to which Ruiko says that there must be "something" if there is that many hits. Continuing on, Kazari says that she can no longer find the website Ruiko was looking for, which confuses Ruiko as she was sure she was saw it about a week ago. Ruiko smells a cover up and talks about on how there is an organization that targets those who get close to the Shadow Metal.

Mikoto and Kuroko later arrive in the office as the former have a bit of time before her next event as Kazari jokes to Ruiko that she might be targeted by the organization who wants the Shadow Metal. Immediately after, Ruiko is attacked by men in hazmat suits. Concerned, Mikoto asks Kazari what is going on, to which he explains that Ruiko is being attacked by someone on the other line. Hearing this, Kuroko and Mikoto mobilized after Kazari says that Ruiko is in Kirigaoka Girls' Academy grounds in School District 18. Kazari is left behind for a backup as they might need to contact Anti-Skill. Arriving there, Kuroko notices them, but Mikoto, seeing Ruiko being held down angers Mikoto and attacks them. Mikoto and Ruiko later prostrate themselves in apology to them after it is revealed that they are the one who clean the grounds after an event to prevent the DNA traces of espers from being stolen by outsiders. Seeing Ruiko as a trespasser in the grounds, it was only natural for them to apprehend her. They are later let go by them. Kuroko says that the rumors of Shadow Metal spread because of the fact that the grounds were heavily guarded to prevent DNA maps from being stolen, and berates Ruiko for being carried away by a baseless rumor, as well as Mikoto for the attack.

The others later arrive back in the office, and much to Kuroko and Mikoto's chagrin, Ruiko then immediately asks Kazari if she had found any new information. Kazari then says that she has done some searching herself but couldn't find anything. Little did they know that Misaki paid Kazari a visit and have read her memories that she and the others are Mikoto's friends, modified her memories so she forgets about the website and have her erase the data of it from her computer, and have programmed her to lead her and her friends to her on the next day. That night, Ruiko introduces Kazari to her parents

The next day, Misaki makes her move against Misaka Mikoto. Kazari, as programmed by Misaki, takes Ruiko and Kuroko away from their proper patrol route. Kuroko realizes that they are in the wrong route, which surprises Kazari truly believed she was going the right way. Then, Keitz appears behind them, pretending to be an outsider in need as a distraction. Misaki later comes out of an alley as they are distracted and uses her powers to freeze their movements, preventing Kuroko from using her powers, and later erases their memories of Mikoto. As Mikoto tries to escape Misaki's clique, she notices Kuroko, Kazari, and Ruiko walk along by. She is relieved and comes towards them, but much to her horror, discovers that they too have been brainwashed by Misaki. Mikoto is greatly angered by this affrontary, but is unable to do anything even if she tries to convince them that she is truly their friend. Moreover, Mikoto has another event to partake in.

Mitsuko, fresh out of her latest event, later meets up with Kinuho and Maaya and later stumble upon Kuroko and the others. Kuroko later airs her frustration on Mikoto coming up to her, making an accusation, and then asking them if they were joking. This surprises Mitsuko, Kinuho, and Maaya, wondering if Kuroko and Mikoto had a fight. Back with Kuroko and the others, she wonders on how Ruiko and Kazari knew Mitsuko. They point out to her that they met when they were visiting Kuroko in the hospital, though this confuses Kuroko as she is not close with Mitsuko. The others can only conclude that there was a mutual acquaintance but cannot remember who.

The girls go their separate ways for the moment, with Ruiko finding a Gekota merchandise that Mikoto might like and tries to send a picture of it to her, but since she has no memories of her, she is confused as to whom she is going to give it to. She then sees MItsuko following Baba Yoshio to a park without people.

Kinuho and Maaya later arrive, searching for Mitsuko in regards to their promise of helping her with the cat of Mikoto's "sister". they apologize to the Psychometer for calling her in vain, to which she says that they could just call her again once they find her. As she leaves, they wonder where Mitsuko could have gone. At this point Ruiko runs into them, to which they ask where Mitsuko is. Ruiko later leads them to the park, where they see their friend on the ground bloody and beaten. Ruiko goes up to Mitsuko's unconscious body and sees what Yoshio has done, becoming enraged. Ruiko asks if it was Yoshio who did this, to which he doesn't deny, still calling Mitsuko trash. Yoshio says that Mitsuko was only doing what she did because Misaka Mikoto asked her to. He mocks her for being a second rate who let others think for them, and even mocks her for even failing at the role she was given. Yoshio says that if they have arrived earlier then they would've seen her like the trash she is. Ruiko is at her breaking towards Yoshio's mockery, but before she can do a thing about it, Wannai Kinuho and Awatsuki Maaya steps forward to confront Yoshio. Kinuho asks Ruiko to get Mitsuko and the cat away from the place. Ruiko tries to protest, but she sees the withheld anger of Maaya, saying that if they don't keep the cat safe then all of Mitsuko's efforts would be in vain. And as ss the waters of the artificial lake rumble and tumble about from their tranquil fury, they tell her that they too cannot hold back their anger when their friend has been insulted.

Seeing this, Yoshio mocks their feelings as he order his robots to attack Ruiko as she begins carrying Mitsuko. His efforts however are prevented by Kinuho and Wannai's intervention and she manages to get away. Wannai uses her power to make Mitsuko lighter for Ruiko to carry, allowing them to get away. Although angered that Mitsuko got away, he is confident that the Type: Mosquito that injected her with drugs would do its side role as surveillance well, believing that as long as she can track her he can retrieve her later.

Meanwhile, Mikoto is still stuck with Misaki's clique, when she finds Ruiko near a hospital. Mikoto, worried, tries to go to her and finds what had happened to Mitsuko. In the hospital Ruiko tries to tell Mikoto about what happened between her, Wannai Kinuho, and Awatsuki Maaya with Baba Yoshio and his robot dogs. All the while, Mikoto blames herself for involving Mitsuko, still believing that it is Misaki's doing. She finds Yoshio's Type: Mosquito on Mitsuko and tries to leave. The girls of Misaki's clique asks for Mikoto to wait for the other members of the clique to arrive, but Mikoto tells them that if they are prepared to kill her to stop her then they should go out of the way. Cowed by her sudden outbursts, the girls can't help but let Mikoto leave. She later uses the mosquito robot that was attached to Mitsuko to track its owner.

Later, as Misaki's cliques wonders on what to do to find Mikoto, the girls wonder where the Queen could be as they believe she could help them, though they had no contact with her since yesterday. Ruiko, who is waiting for Kinuho to report on Mitsuko's condition asks who the Queen is, to which Maaya says is Shokuhou Misaki, and that the girls of her clique call her the Queen. Ruiko recognizes her name as the esper who can manipulate memories. Kinuho then comes back and reports on how Mitsuko has no external wounds that are likely to give her scars and that the nanodevice will be sent to a specialty facility. And with that, the only thing they need to do is to discover the secrets the cat holds.

Calling the animal psychometry girl from Tokiwadai again, she says that her power allows her to pick up fragments of the cat's qualia. So she says it is not like she can communicate with it, but she can understand aspects of what happened that the cat could not. Using her powers on the cat in the time around midday yesterday, she begins to see what the cat saw. She finds the location and sees Misaka 10032's body collapsed on the ground, as well as Keitz and Misaki, though she does not recognize them especially Misaki for she is far away from the cat's view. She tells them of their conversation, and then finally something that Ruiko recognizes: "What happened to Auribus oculi fideliores sunt?"

Kinuho says that it is Latin meaning "Believe more in what you see that what you hear", and makes Maaya wonder if it is a code. The session ends as the girl says that the cat's attention turned elsewhere. After thanking her, Kinuho tells Ruiko to contact Mikoto since Mitsuko is incapacitated it would be better if Mikoto knew what has been disocovered as soon as possible. With that the two thanks Ruiko, and tells her that they will be in Mitsuko's hospital room. Ruiko tries to contact her but realizes (because of Misaki's brainwashing) that she doesn't have Mikoto's number, however, finds out that she does, confusing her. She would later talk to Kuroko about on how they are friends with Misaka Mikoto, much to her disbelief. Kuroko questions Ruiko's theory on Shokuhou Misaki manipulating their memories. Kuroko then asks why she didn't contact Kazari. Ruiko, who has already suspected that Kazari has been the first one to have been brainwashed by Misaki, says that she is hesitant in telling her. In the end, she tries to call Mikoto as she has a message for her.

After Ruiko introduces herself, she tells Mikoto about the information they had gathered from Misaka 10032's cat. Mikoto says that she has no clue what that girl with the man from the cat's memories, who she says is likely Misaki, is talking about. Just then, Ruiko says that there is something that she is knowledgeable about that came about in the conversation that the cat has heard, and that she also wants to know whether she and Ruiko know each other. Ruiko requests that they should meet each other, to which Mikoto says her location and it is in School District 15, which Ruiko notes is quite close. Ruiko asks for Mikoto to stay there as she'll ask Kuroko to teleport her to where she is, much to Kuroko's frustration. After Mikoto discover that Kuroko is with Ruiko, Kouzaku Mitori's Liquid Shadow dummy approaches her, telling her that she wants her to tell her something. Mikoto, already suspicious, says that she is quite busy and has no time to talk to strangers, but she'll make an exception to those who are connected with the guy (Baba Yoshio) who hurt her friend. Mitori is unperturbed and shows that she has Kazari hostage.

Ruiko then contacts Kazari to know what's going on, to which Mikoto detects using her powers. Ruiko is not present in the battle that ensues with Kouzaku Mitori and the aftermath, but is later with the others in Judgment 177 Branch Office, and Ruiko later has Misuzu and Kazari sleep in beds and gives them medicine. With that they discuss about the situation at hand. Mikoto confirms to Ruiko that the girl that Misaka 10032's cat saw is definitely Shokuhou Misaki and has abducted her "sister. Ruiko then mentions Auribus oculi fideliores sunt, an urban legend website she knows of. Kuroko questions why Misaki would be interested in that, to which Ruiko says that the site not only gathers information about urban legends but has people go out and verify it. She relates on how yesterday after the midday break, the time after Mikoto's sister was abducted, she was out looking for Shadow Metal and had Kazari look up the site. When she returned Kazari says that she couldn't find it, prompting her to find it on her own only to find that the website got buried by a bunch of dummy sites. Ruiko explains that once something is on the Internet it can never fully be deleted. She says that somehow someone is trying to hide the website by making dummy pages that will have higher spots in the search results. Mikoto can only assume that there must be something in that website that someone doesn't want to see. Kuroko then mentions that Kazari would have noticed something and had the skills to search for the cause of it. Mikoto conjectures that someone had detected her actions and attacked her. She imagines Misaki doing it, manipulating Kazari to delete the data and then searching her memories to find that she is friends with Mikoto. Ruiko says that they have to force the clues together to reach the conclusion, but says that there still must be something remaining in the computer that could help them.

Using her powers, Mikoto recovers the deleted data. She finds a picture of Misaki from the website, confirming her suspicions. Mikoto asks Kuroko if she can identify where she is, to which Kuroko says that it might be School District 2 due to the building in the background. Before Mikoto can run off to confront Misaki herself, Ruiko asks Mikoto if their memories were truly altered, and that if they are truly their friends, to which Mikoto says that she will drag Misaki here and that they should wait.

Ruiko becomes restless at waiting, to which Kuroko says that Mikoto was the one who told them to wait and that she shouldn't worry. Moreover, she is still honestly unbelieving that they had their memories erased. Ruiko comments on how having her memories of her friends erased would be bad and that she'd hate it. She later finds Kuroko looking up a list of girls in the Bank, to which Kuroko says that she saw the one that attacked Kazari, and that she had been looking for her in the Bank based on her powers, as well as her sending the liquid metal and knife for forensic analysis. Ruiko becomes excited over this, to which Kuroko says that she is merely acting as a member of Judgment, and that she cannot hand over the investigation to a normal person. She then says, with much embarrassment, that she can make an exception as the situation is urgent and that sharing information would be beneficial. Ruiko then has a smug look on her face, much to Kuroko's consternation as Ruiko begins helping her.

Ruiko later discusses her hypothesis regarding Kazari being controlled by Misaki since yesterday, leading to them to conclude that is the reason why Kazari took them to the wrong patrol route. Ruiko then says that they should keep it a secret from Kazari, saying that she is the type that to feel responsible when no one is to blame. Just then, Kazari has woken up from the infirmary opens the door and asks them to tell her exactly what they are talking about, to which Kuroko agrees, much to Ruiko's shock. She however, says that Kazari should first make some tea. Kuroko whispers to her that she admires that she is protecting Kazari, she says that she isn't that weak to have that break her. After being briefed about it, Kazari is dismayed for being manipulated. Kuroko however says that after their break they should restart their investigation, and asks Kazari if she can look through the Bank for anyone suspicious. Kazari asks if she is sure that she can trust her, to which Kuroko says that they do not have time to have a detailed examination as they need her skills now. She then tells her that if she is really worried, then she can do her work in front of them. Kazari goes right to it, impressing Ruiko.

As they investigate liquid metal, Ruiko notes that only two companies that have developed liquid metal have survived. Kuroko says that the companies have no record of loss or theft, which opens up the possibility that someone inside the company is helping the esper using liquid metal (Mitori). Just then, Kazari has finished the search according to Kuroko's specifications and they discover that the name of their attacker is Kouzaku Mitori. Finding information about her, Kazari says that Mitori is in the Reformatory for an attempted terrorist attack 14 months ago. Ruiko asks if she escaped, to which Kazari says that if she did, then Judgment should've been notified. Kazari asks again if Mitori truly was the culprit, to which she confirms. Regardless however, Kuroko wants to double-check and says she wants to go to the Bank's control center. Kazari then asks what Ruiko would seeing as she will likely not be allowed there as she is not a member of Judgment. Ruiko says that she will pass and asks about Misuzu, to which Kuroko says that she has explained the situation to Konori Mii, their senpai. She says that Mikoto wished for Misuzu to be told that she collapsed of heatstroke and that she will be kept in the office for protection under the guise of getting a new ID issued.

With that they all leave the office, with Ruiko wandering about the district while there is an on-going event. She then realizes that one of the defunct liquid metal factories is nearby. As she ponders this, she finds a certain spiky-haired boy at the end of his wits—Kamijou Touma—asking people if they have a protective charm for the Borrowing Race. Ruiko sees him as he complains about his quarry, being in the city of science and all, and laments his misfortune. Ruiko has the protective that was given to her by her mother, but doesn't want to part with it. She is sorry that she can't help Touma and tries to move away from him, but he somehow manages to end up where she is despite moving a bit of a distance away. Ruiko notes Touma's perseverance, as he still has yet to give up, and that though he will end up in last place regardless, he'll still have points. Seeing that Touma seems like a nice guy, she finally calls out to him, hoping he will not throw it away. Ruiko says she has one, much to Touma's relief, he tries to touch it, but realizes he is using his right hand. He pulls back and grabs the protective charm with his left hand instead, not wanting to negate the benefits it gives.

Ruiko says that it may be beaten up it is still important to her, Touma understands. However, he realizes that he can't let her wait for him to finish the race, to which Ruiko says that the can just meet later in front of a store. She also says that if he can't meet her then he can just take it to Judgment 177 Branch Office. With that they're finally in agreement. Ruiko introduces herself as Saten, while Touma thanks her and introduces himself as Kamijou Touma, saying that he'll make sure to return it.

Despite better judgment, Ruiko goes to the factory alone and finds it completely abandoned, or so she thought. She later espies men moving equipment into a room, and discovers that the building still has power. Ruiko tries to go into the opened door as it closes, and successfully manages to do so. She however is too late to realize that error of her judgment, not knowing how she is supposed to get out. Ruiko tries to contact Kazari but is interrupted by people coming down the adjacent hallway. Ruiko later flees and manages to make it deeper into the facility. Xochitl finds her however, taking out her Macuahuitl, a traditional Aztec sword, and puts it up Ruiko's neck. She asks Ruiko what she was doing there, and tells her not to turn around. She instructs her to forget everything she saw and leave the place without a word. Ruiko agrees and tries to run off, but the turns around to say to Xochitl that she doesn't know how to get out on her own, angering Xochitl for not following her instructions. Suddenly, something slices up behind Ruiko, cutting her hair and bag. There Mitori's Liquid Shadow puppet appear, prompting Ruiko to flee. Mitori asks Xochitl why she let her go, to which she says that since their plan is in the final stages, Ruiko wouldn't be able to do anything at this point. However, Mitori says that that is no reason to let her leave. She tells one of the thugs there to capture the girl who ran off, worrying Xochitl. What's more, the Professor begins calling her as well.

Ruiko gets captured by the thugs. The thugs ask her what they should do with her, to which Mitori replies that after she gets to tell them what she was doing there, they can dispose of her as they see fit. Immediately after Xochitl comes to the rescue, defeating thugs easily with her Macuahuitl. Seeing this amuses Mitori, believing it to be either a betrayal by Xochitl or her caring about Ruiko. She tells Mitori that she doesn't care about that idiot behind her (Ruiko) but says the real traitor is Mitori herself. Xochitl then explains that their current mission has nothing to do with what the Academy City Board of Director wants and that Mitori is using her position as a go-between for them and the Board of Directors to coerce MEMBER to act for a client. She says that the Professor has grown suspicious and instructed her to track down her betrayal. She says that it doesn't matter where the instructions came from but she must punish a traitor.

Mitori says that if Xochitl tries to do that in the factory it would be a one-sided slaughter. Xochitl however states that Mitori may be sure that she is safe where ever she is hiding but she is not aware of all her spells. Mitori assumes that Xochitl may be bluffing but takes into account Xochitl's powers coming from outside Academy City and that she might produce some unexpected phenomenon. Not wanting to screw up, Mitori retreats. As her liquid metal puppet becomes more fluid, she gives Xochitl some advice. If Xochitl has something to return to she should leave Academy City now. Xochitl says that she has nowhere to return to, and that there is someone in Academy City that she must pursue at the risk of her own life. Mitori can only reply that Xochitl is quite a maiden. With that over, Ruiko comes toward Xochitl to thank her, now finally remembering her as the girl from yesterday, but is greeted with a bonk to her head. She tells Ruiko to not thoughtlessly approach the dark side of Academy City without the means to protect herself or the willingness to throw away her life. With that lecture over, Xochitl tells Ruiko to come with her as she will show her the exit.

After finding the exit, an irritated Xochitl tells Ruiko to get lost. Ruiko asks what the melty person (Mitori) was after, to which Xochitl says not to get involved. However Ruiko is persistent, forcing Xochitl to acquiesce. She then says that she doesn't know what Mitori is after as they (MEMBER) were made to act on false orders. However, it is revealed that Xochitl asked Mitori about the strange part of their "mission," and though Mitori evaded the question through how she acted, Xochitl was able to determine that she and whoever hired her wanted to use Misaka Mikoto. Their conversation is overheard by Kamijou Touma.

Touma who has overheard the conversation between Xochitl and Ruiko, and without much fanfare hands back the protective charm back to her and then heads out to where Mikoto is. Meanwhile, Ruiko contacts Kuroko and Kazari about the situation Mikoto is in, and then later goes back to Judgment 177 Branch Office. Kuroko then teleports to School District 2, as the Level 6 Shift attempt on Misaka Mikoto takes place. Ruiko and Kazari later aid Kuroko as she does battle with Kouzaku Mitori.

Kuroko teleports from building to building trying to find Mitori. She recalls Misaki's informing her, in that Mental Out isn't very effective on Mikoto, and as such the Liquid Shadow puppet cannot give Mikoto orders. This leads her to conclude that Mitori can only guide Mikoto's psyche if she is nearby. However, with such a high concentration of research facilities near where Mikoto is, Kuroko contacts Kazari and asks her to check every camera within 800 meters of School District 2's Judgment building. She tells Kazari to see if she can find Mitori on one of the cameras as well as a list points the cameras do not cover. Kazari asks Kuroko if she needs backup, to which Kuroko says they do not have time.

As Kuroko teleports into one of the buildings, Mitori has her puppet slice through a door to attack her. Kuroko then proceeds to engage the puppet in combat. As she battles, she finds out where Mitori puts the camera on her Liquid Shadow puppets so she can see, which is on her neck. She attacks it with her darts, disabling Mitori's secondary senses, and forcing her to use echolocation to grasp the situation, Mitori's primary sense for her puppet. She then uses a small device to deafen her ability to echolocate. Kuroko then teleports away as the puppet is preoccupied, trying to search for Mitori. However, the facility is so vast, she requires the aid of a clue. Back in Judgment 177 Branch Office, Ruiko manages to find Mitori in one of the cameras. Kazari contacts Kuroko, telling her of Mitori's moving into an alleyway three minutes ago, though she can't tell what building she's in as she hasn't been seen in the other cameras. Kuroko then rushes toward the likely location of Mitori.

Kuroko asks if they're sure Mitori hasn't been seen in any other camera, to which Ruiko confirms. Kuroko notes that Mitori would show up in the cameras if she moved into another building. Seeing this, Kuroko manages to pinpoint the building where Mitori is likely hiding in. She orders Kazari and Ruiko to turn all nearby movable cameras toward the building as she teleports in.

Back with the puppet, Mitori is able to pierce the device, but then realizes that the security cameras likely gave her location away. She then has her puppet slice and enter a sewer pipe to head to where Kuroko is going. Kazari notices this as well, and reports it to Kuroko, confirming to her that the place where Kuroko is in is where Mitori is hiding. Mitori, turns her attention to Kuroko, and uses the cameras of the Homing Cameras that is used for Daihaseisai events to target her. Mitori observers the battle directly during the puppet's confrontation with Kuroko in the building. After Kuroko uses the anti-listening device on her puppet again, Mitori uses the puppet to attack her, though could only spread her attack as she could not tell how high up Kuroko is. Despite being hit on the side and on the arm, Kuroko teleports away and applies a small a balm on her injuries. While doing so, she believes that Mitori is in the building based on the puppet's actions and that she is in the upper floors. After treating her wounds, Kuroko pursues Mitori from below, though notes that she may be overlooking something.

Meanwhile, back in Judgment 177 Branch Office, Ruiko and Kazari becomes worried of Kuroko's injuries. Kazari, as she watches the cameras, later catches the Daihaseisai Homing Cameras surrounding the building where Kuroko is in despite being no events. Kazari researches that Anti-Skill apparently used them to see if anyone has yet to be evacuated but notes on how the powerful electromagnetic waves there are too powerful for the cameras to approach. Ruiko then gets the idea in having them use the cameras to aid Kuroko, leading Kazari to eureka moment. She asks Ruiko how long the cameras were there, to which she says that they have been there since Kuroko entered the building. Kazari then reports this to Kuroko, giving to her the possibility that Mitori is not inside the building but somewhere else.

With this new knowledge, Kuroko continues her pursuit of Mitori inside the building. Kuroko finds the last blind spot of the building, only to find that she isn't there. Kuroko goes over thoughts once more, and discovers that Mitori may be hiding in the sewers and that she was led into a trap by Mitori. Mitori's puppet later catches up to Kuroko a ventilation duck. As Kuroko uses another anti-listening device to seal her echolocation, Mitori turns one of the Homing Cameras she has hacked toward the blind spot. Considering the lag when Kuroko teleports and the locations where she is likely to jump to, Mitori has her puppet fire a knife hidden inside it towards Kuroko. However, unbeknownst to her, Kazari has hacked that particular camera to display dummy footage, allowing Kuroko to escape.

Kazari later becomes exhausted after hacking the camera and is later fanned by Ruiko, praising her for her hard work. Kuroko later manages to find the real Mitori and defeat her, ending her manipulation of Mikoto.

After the battles come to a close and Mikoto is turned back to normal, Misaki uses her power to restore the memories of Kuroko and the others' memories of her, though modified the events somewhat for them, making the believe that they were out trying to catch terrorists targeting the festival to avoid contradictions. Apparently all to hide the existence of both Exterior and the Sisters from public knowledge, as well as passing along the information on the virus to Heaven Canceller to treat the sisters. Mikoto's not participating in the festival events on the second day was changed as well to that of her eating too much and having her stay in the bathroom all day, much to her chagrin.

All the girls visit the field where the bonfire folk dance is being held and comments on how they are unable to dance. Mikoto goes away to buy them all drinks. In the meanwhile, Kamijou Touma later meets up with Ruiko, and thanks her for the protective charm she lent. Touma offers her to buy her some food to make it up to her, though she says that it is all right. Mikoto later comes around with the drinks, and finds Touma talking with Ruiko. Touma says that he borrowed a protective charm from her, confusing Mikoto though later figures out it was for the borrowing race. Mikoto's stutters and awkward way of presenting herself to Touma does not go unnoticed before the eyes of Ruiko and Kazari.

Capitalizing this new found knowledge, Ruiko approaches Touma and asks him to dance with her around the bonfire as a way to thank her for lending him her protective charm. Touma is fine with the idea, though asks if she is sure with it, to which confirms. Ruiko then tells Touma to go on ahead, leaving the girls alone. Mikoto is utterly shocked by what has transpired, but with a knowing look between Ruiko and Kazari, they make their move. Ruiko fakes an ailment finally catching up to her, prompting Mikoto to ask her if she is okay. However, Kuroko suddenly figures out their ruse and tries to tell Mikoto, but Kazari comes up behind her and covers her mouth. With this ruse finally set up, Ruiko says that she can't move but tells Mikoto that she can dance with Touma in her place. Mikoto becomes embarrassed by this, and makes up a bunch of excuses. Fed up with this, Ruiko forces Mikoto to say that she wants to dance, to which she does.

The girls later see Mikoto dancing with Touma which is unceremoniously interrupted by Kuroko, teleport dropkicking Touma away, much to Kazari and Ruiko's disappointment.

Toaru Majutsu no Index Movie: Miracle of Endymion

 * Main article:Toaru Majutsu no Index Movie: Miracle of Endymion

She plays an extremely minor role in the movie, often just hanging around with Kazari. She is the one who calls Mikoto on how Meigo Arisa has been abducted. Later, when Kazari states that they need to destroy the explosive bolts of the Endymion in order to prevent it from crashing down to earth, and that they are in need of people to do so, Ruiko tries to offer her "services", showing off her bat, but is then interrupted by Tsuchimikado Motoharu, who hijacks their communication lines just to say that he is offering them his services. She later witnesses the Miracle of Endymion, and the space elevator no longer being in danger.

Toaru Kagaku no Railgun Special 1: "MMR: More Complete Railgun"
Ruiko first appears in the beginning of the special, flipping Uiharu Kazari's skirt in a strange accent. The scene where Ruiko and Mikoto are purchasing crepes in the first episode is parodied, here Ruiko receives Alastor from ‘’Shakugan no Shana’’ instead of a Gekota toy and offers it to Mikoto. Later both Ruiko and Kazari are horrified after they witness Kuroko's neck being broken multiple times by the Tokiwadai Dorm Mistress, afterwards they discuss rumors about her being a former soldier in the jungle snapping people's necks. In a later scene Ruiko is seen sighing in a classroom wanting to eat shibazuke. In a later scene Ruiko's teacher asks her what would happen to the cat in the box (the experiment is similar to what Komoe demonstrated in Toaru Majutsu no Index) which looks similar to Sphynx, Ruiko answers that the cat would be either dead or alive and is proven wrong when the box reveals the Palm Top Tiger from ‘’Toradora!’’.

In the final scene Ruiko, Kazari, and Kuroko listen to Mikoto and her suspicions of the many wind turbines in the city even when they are inland. Both Ruiko and Kazari are both convinced by her that extraterrestrials are involved with this but is later told by Kuroko that in Academy City anything can happen.

Being a photoshoot model under the sun isn't easy, you know
Set during episode 13, Ruiko accidentally takes a suntan lotion filled with aphrodisiacs, courtesy of Kuroko, that was meant for Mikoto. Aroused, she tries to see Kazari's panties, and is quickly told by her that since she is wearing a swimsuit, she doesn't have any on. However, this only makes Ruiko want to see even more, and soon chases Uiharu. She later comes to her senses and apologizes to a scared Uiharu, though is quickly told by Mikoto that she was a victim herself.

Extra Franchise Cameo
Saten appears quickly for a second in Ookami-san and her Seven Companions (also produced by JC Staff Animation Studios), looking uninterested at the screen, as a potential bride candidate for the boy millionaire Nezumi Chuutaro.

Abilities
Her ability while using Level Upper is Aero Hand (空力使い (エアロハンド) ), a power that should allow her to propel objects using ejection points of air, though, she can only move small leaves in the palm of her hands. Once Level Upper was reversed, her ability level returned to 0.

Other abilities
She also is very athletic, being capable of running for a noticeably longer time than most students during her extra classes after the Level Upper incident, and was capable of quickly reaching the top floor of the large building that housed the Child Errors from the very bottom floor. Also, she is able to dodge the attacks of full armed and dangerous Powered Suits and hit them with a baseball bat. She is also capable of destroying expensive technology with merely a swing of a baseball bat. Both these situations emphasize her strength and agility.

In the Silent Party arc, she and Kazari are able to memorize an entire manual of instructions on how to pilot a giant mecha in one night and able to apply it in battle. This is exemplified by Ruiko and Kazari easily defeating two mobile weapons. It should be noted that she has not shown any sign of this sort of intelligence anywhere else in the series, and her ability to do this might have been due to it being on the spur of the moment with a lot being at stake or simply another aspect of Cloverfield as this was an anime original scene.

Design evolution
Haimura designed Ruiko for the Toaru Kagaku no Railgun manga. Originally, he thought that she was a victim-type of character that needed protecting, that is until Kamachi told him to make her more bright and carefree, which forced him to redesign her. Haimura gave Ruiko a flower hairclip to match Uiharu Kazari's flower headband.

Trivia

 * She displays impressive skill in sewing.
 * She and Uiharu Kazari both have cameos in both openings of the first Toaru Majutsu no Index anime, although with shorter skirts.

Quotes

 * (To Uiharu)" I'm Level 0. No powers. But I don't worry about that sort of thing. As long as everyday is fun, I'm okay with it."
 * (To Uiharu on the phone)"I didn't like being so powerless. But I couldn't give up on my hopes...Mama..."
 * (To Uiharu)"I'm sorry...I got you involved in something dumb...I kept secrets from you...and made you go through all of this...Only a bit more, and I might have lost something far more important than powers..."
 * "There's no way it'd go so well. But...Let's keep trying."
 * (To Uiharu)"I'm not going to give up anymore. Yep, never again."
 * (To Mikoto)"It's not trouble to us. But instead of worrying about you after you're gone, I'd rather go with you and help you. Because that's what friends are for."
 * (To Therestina)"Don't you dare lay a finger...on my friends!"
 * (To Mikoto)"But don't forget this. We're here for you. If you can't do it on your own, please let us know anytime, okay?"