Takitsubo Rikou

Takitsubo Rikou (滝壺 理后) is a character introduced in Toaru Majutsu no Index. She is a member of ITEM, a mercenary group in the dark side of Academy City. Despite her lethargic appearance, she is the core of the team due to her AIM Stalker. After constant use of the Ability Body Crystal, and the dark turn their leader Mugino Shizuri takes culminating with the execution of Frenda Seivelun for her betrayal, she becomes estranged from the group, and later flees and falls in love with Hamazura Shiage, the third protagonist of Toaru Majutsu no Index. Much of the story that focuses on Shiage revolves around his and Rikou's struggle against the Dark Side of Academy City.

After the events of World War III, Mugino Shizuri reconciles with the remaining members and reforms the group. The organization becomes the only known faction from the Dark Side of Academy City that fought in the factional war on October 9 to have not been disbanded after the war.

Appearance
Rikou is a high school girl who often looked tired. Her black hair was cut evenly at shoulder length. In her original appearance, she is usually seen wearing a pink track suit that functioned as casual wear and sleepwear for her, to the point where Shiage believes that she would probably wear it to a wedding or funeral. According to Saiai, Rikou's track suit is "overflowing with practicality," likely indicating that Rikou chooses her clothes based on functionality and not on appearances.

In her appearance in Toaru Kagaku no Railgun, she only wears track pants with a white shirt. Her large breasts are apparently hidden by her track suit.

Personality
Paired with her tired looking appearance is her lethargic demeanor and is referred to be an airhead, often shown in illustrations as staring into blankly staring into space. She can also sleep with her eyes open. She has shown to rarely express her inner-thoughts, and when she does, she sometimes does it without any emotional expression, an example of this is when she nudged Shiage that they should leave the family restaurant they were in as Mugino Shizuri needed to visit Frenda's grave.

Despite this subdued demeanor, she truly does care about her fellow ITEM members, rooting for them when they are down as with the case of Frenda failing to stop Misaka Mikoto when they arrive to back her up. In fact, though the others can easily act as the most casual during non-missions, her subdued demeanor belies her kind nature. She is described as a valorous girl, despite her involvement in the Dark Side of Academy City. This indicates that she retains her humanity despite her involvement. This is backed up by Shiage's observations of her after she let him escape and how she may have been affected by Shiage's lamentations regarding nameless corpses being burned in the Dark Side of Academy City and how he might end up as one. Moreover, not only is she kind but quite selfless, as exemplified in the aforementioned sentence as well as showing in many opportunities she offers herself as a bait to lure out enemy while her friends escape regardless of her own physical state; in other times she refutes the possibility of being rescued from danger as the risk is too high. It is likely because of this selflessness that Hamazura Shiage wants to "bring happiness" to Rikou if possible.

Rikou is in love with Hamazura Shiage and has shown to be quite possessive with him, willing to argue with a child over him, and has shown strong behavior towards any sign of unfaithful behavior unbecoming of her, to the point where Hamazura described that attitude as "a dangerous light in her eyes." Moreover, she has shown to be quite impatient towards Fremea Seivelun, often warning Shiage of threats of violence against her when she acts brattish towards them, forcing Shiage to calm her down, an example of this is her wanting to perfrom an iron claw on her. Finally, as of Shinyaku Toaru Majutsu no Index, they seem to act like to act like two married couples with Fremea as their child. This is shown by a dialogue with them while walking Fremea back to her dormitory regarding the need for detergent, at which point Shiage comments on how her attitude lacks sex appeal.

Background
Not much is known about her past, but she herself states that ITEM is the only place she belongs to, this might imply that she is a Child Error.

As she is an esper, she likely went through to the Power Curriculum Program. After discovering the rare potential of her AIM Stalker of making her the 8th-ranked Level 5 or even something much greater than that, researchers ran a simulation on her with Tree Diagram but it found that making her one had conditions that were too severe. As such the researchers were forced to turn to the research of the Kihara Family, specifically the Ability Body Crystal as it had similar effects. However, according to the ITEM liaison, simulations using the Ability Body Crystal had hopeless results. Despite this the researchers continued to tamper with Rikou's body as the possibilities of her power was too valuable.

Her entry into ITEM with Mugino Shizuri giving her Ability Body Crystal was unbeknowngst to them, likely part of the research on Rikou. Due to her knowledge in the inner-workings of Rikou and her AIM Stalker, it is likely that the ITEM liaison was the one recruited her into ITEM for this purpose.

Battle Royale Arc

 * Main article:Battle Royale Arc

Prior to the start of the events of October 9, she likely participated in the killing of SCHOOL's sniper, though they were unconcerned on why they targeted Oyafune Monaka in the first place. She first debuts along with all the other members of ITEM immediately after the assassination attempt on Monaka's life by SCHOOL in a family restaurant. Kinuhata Saiai asks Rikou on her opinion regarding a movie from the Hong Long Red Dragon Film Company, as she is excited for it, though Rikou only absent-mindedly replies that there is a signal coming from the south-southwest. After Hamazura Shiage mulled on the uneven male to female ratio as well as Shizuri finishing her lunch, Shizuri begins saying on how before noon, someone attempted to assassinate Monaka. Shizuri states that the higher-ups want to them to take action regarding that. Frenda comments on that she doesn't have information on that. Hearing this, Shizuri orders Shiage to send the details of the incident to everyone's cellphone. With a halfhearted response Shiage does so, though he accidentally sends a pornographic video (likely related to bunny girls) he downloaded from the Internet. When the ITEM members see this, all of four snapped their cellphones shut and looked at him with scorn. Shiage tries to amend his mistake by trying to send the information again, but he however is chastised by them. Shizuri is lost in words, only being able to say his name. Frenda says that he is disgusting. Kinuhata Saiai asks if Shiage likes bunny girls. Finally, Rikou says that she is rooting for him. Trembling at their words, he makes sure at sending the information to all for them.

Their conversation begins with Kinuhata Saiai pointing out on how she was sure that they took out SCHOOL's sniper three days before. Mugino Shizuri says that SCHOOL likely hired a new one and ignored their "warning". Frenda Seivelun states that back then they didn't debate why they were targeting Monaka, but realizes that there must be something up if they still wanted to assassinate her despite her low value even amongst the Board of Directors. Rikou adds to Frenda's conclusion, repeaing what Shizuri says. As Shizuri tries to think on the reason why SCHOOL went out of their way to try in killing Monaka again despite her low value, she asks for Shiage's opinion. Shiage tries to give an answer but his response didn't actually have anything in it. Disappointing everyone, with both Frenda and Saiai calling him disgusting, while Rikou says she'll root for him even everyone else is calling him disgusting. With this disappointment, Shiage kneels on the ground and is promptly ignored. Shizuri goes back on topic and proposes that SCHOOL targeted Monaka because there's no value in killing her. Saiai is confused, to which Shizuri says that SCHOOL probably didn't care who it was as long as it caused a disturbance, choosing a VIP whose death whose death wouldn't have much of an effect and didn't have strong security. Frenda then states that she feels sorry for Monaka. Feeling proud, Shizuri gives her hypothesis on what SCHOOL is after, starting on how if a VIP of Academy City are in danger, people are called in from all sorts of places. She says that roads are blocked off in order for ambulances to travel on as well as important people from various medical industries gather at the hospital for them. Saying this, Shizuri asks on what would happen if someone attempted to assassinate a VIP, and she answers on how people will be called in to protect the facility where the VIP will undergo treatement. Shizuri concludes that SCHOOL will do something amidst the confusion. Saiai states that their methods are boring. Shizuri then speculates on what the facility they would be targeting after the creating the commotion. Frenda concludes that Monaka was just SCHOOL's insurance for their plan to be in order and that they are still planning on attacking their real target, to which Shizuri agrees. Shiage then speaks up again, asking if what SCHOOL did was really an attempted assassination. Shizuri says it probably didn't matter as Monaka may be revived by Academy City's mysterious technology even if she died. Shizuri then orders that they need to find the facilities that have insufficient security due to the assassination attempt. She then adds taht they also need to see what has changed had the assassination been successful, stating that SCHOOL may have made a situation where they could move whether the sniper succeeded or not, indicating that there might be a facility that has its security reduced regardless as it may be where SCHOOL is headed. She then orders Shiage to find a car for them as they may be heading out soon. Shiage becomes irritated on how Shizuri said her orders, but he is forced to acquiesce. However, Shiage complains on how he was once the leader of over 100 Skill-Out, to which Shizuri says that it is true though she doesn't his point. Shiage then leaves to find a car with a heavy heart.

After Shizuri's argument with the ITEM liaison regarding their next job, to which she later approves after seeing that they are after SCHOOL, the girls get on the car Shiage had just stolen for them, impressing Shizuri. Shiage asks where they are going, to which Shizuri states that they'll be going to Kirigaoka Girls' Academy in School District 18 as there is a particle engineering laboratory nearby that she believes is SCHOOL's target as the place has become disrupted after the assassination attempt on Oyafune Monaka. Shizuri mentions that there are multiple places that she suspected but states that the particle engineering laboratory. Hearing this, Shiage asks what they are after there, though Shizuri says that she doesn't know, but says that it is better than dealing with the whole Oyafune Monaka thing. Shiage then starts the car. Rikou then asks if Shiage has a license, to which he responds by saying that he doesn't need a card to drive, only skills. He then drives ITEM with the automatic transmission car.

ITEM and SCHOOL then clash in the laboratory. The latter apparently not risking a battle later tries to escape in a station wagon. Not wanting to lose her quarry, Mugino Shizuri later takes Rikou with her (likely because she is the only one who can track SCHOOL) and leaving Saiai and Frenda behind. Shiage asks where Saiai and Frenda is, to which Shizuri says their battle back in the laboratory won't be enough to kill them. As Shiage follows the station wagon, Shiage sees her sporting the marks of battle, with her face swollen and clothes burned. Shiage asks what had happened, commenting on how she's supposed to be the 4th-ranked Level 5. Shizuri then says that SCHOOL had a Level 5 as well, the 2nd-ranked Kakine Teitoku. However, Shizuri comments on how in spite of him, they took care of one of them. Shiage then asks what she'll do when they caught up to the station wagon, to which Shizuri says that they'll defeat them and take back what they stole. Shizuri then says that they stole the Tweezers, though Shizuri fails to explain it to Shiage, stating that only he needs to do was to catch the station wagon. Shizuri then begins doubting that they can catch SCHOOL with the car they have, to which Rikou says not to worry. Rikou says that her AIM Stalker can track down the owner of any AIM dispersion field she has recorded, as such she can search and find them even if they leave the solar system. Shiage then reassures Shizuri, saying they have an excellent navigator, as such they won't get away. Suddenly, they see a mobile crane before them piloted by a certain girl, intercepting the car ITEM was in. With her skills, she is able to hit the car, pushing it towards a wall. Mugino Shizuri explains to Hamazura Shiage that the ones who are attacking them are SCHOOL, wanting the station to get away. The Girl backs up the mobile crane for about 10 meters as she tries to strike the car again. Seeing this, Shizuri orders Shiage to smash the windshield of the car as it had crush the doors too much. They are able to escape the car just in time as the Girl crushes it with the wrecking ball and later explodes. With the crane's engine apparently stalling, the Girl comes down to go after them personally. Shizuri tells them that they should split up. Shiage asks why she couldn't stay and fight, to which she says that she is after the Tweezers in the station wagon they were chasing, and does not care for subordinates like the Girl in the dress. Furthermore, Shizuri states that the Girl's power is troublesome. With that they leave in different directions.

Rikou was with Shiage when Shizuri orders him to dispose of a body. When Shiage becomes stricken with terror at the thought that he will end up as a nameless corpse like the one he had just disposed, Rikou asks him what's wrong. Shiage asks what exactly human life is as he stares upon the furnace where the corpse is being turned to ashes. He continues by asking why a Level 0's life is such a cheap thing. Rikou continues to call out to him but he continues to stare into the fires of the furnace. She later separates with Shiage and meets up with the rest of ITEM. There she talks to other members on what Shiage said in the furnace. It is unknown what the others thought, but is likely Rikou now cared for Shiage's well-being..

They are in their Private Salon in School District 3, regrouping with the rest of ITEM minus Frenda. When Shiage arrives after escaping the Girl in the dress of SCHOOL, he asks where Frenda is, to which Shizuri says that she is gone, dead or captured. She says that in a manner in which she is not particularly caring of her fate only inconvenienced by it as there are only three members left of ITEM that could take SCHOOL down. Shizuri then becomes optimistic as they have Rikou for searching. Rikou notices Shiage is hurt, but tells her to not mind, he then asks what they are going to do now as SCHOOL has already stolen the Tweezers. Shizuri asks Rikou if searching for Dark Matter is fine, to which Shiage asks who that is. Shizuri answers that Dark Matter (Kakine Teitoku) is the one who leads SCHOOL. Rikou then prepares to use the Ability Body Crystal to use her power. Here, Saiai sympathizes with Rikou's handicap, as she is unable to activate her power without the use of the drug. After licking the powder of the Ability Body Crystal, Rikou's power begins to activate and searches for Teitoku. There, she concludes that he is within the building. Before they could react, Kakine Teitoku himself appears before them, kicking down the door to their salon. Teitoku tells them that he has come to declare victory, but Shizuri just mock him for being the Spare Plan and running away a while ago. The two of them banter regarding the teammates SCHOOL lost thanks to ITEM. They are however interrupted by Saiai picking up table and smashing it on Teitoku. However, his expression remains unchanged, only exclaiming that what she did hurt. Seeing this, Saiai runs towards a wall and destroys it with her fist. She then grabs Rikou and Shiage, winking towards Shizuri as she leaves into the hole.

She then knocks out every other people she comes into contact with, not taking her chances if they are subordinate members of SCHOOL or not. Saiai then asks Shiage to get a car for them. She tells Shiage that one of the reasons SCHOOL is there is for Rikou, since they know where their hideout was it is also likely that the know all of their other information, and it is likely that they have discovered that they can be searched out through the use of Rikou's power. Saiai states that if Rikou is killed, ITEM will be restricted as she determines if they are the chasers or the one being chased. She continues by saying that as long as Rikou is fine they can still turn the tables around. She urges him to get a car and go into a hiding place where it isn't an ITEM's hideout. She then gives Rikou a stun gun, saying that she needs a weapon as she's always staring off into space. Just then there is an explosion due to Shizuri and Teitoku's clash, to which Saiai goes after telling them to hurry.

As Shiage and Rikou try to escape by elevator, they come upon the 25th floor of the building. However, much to their misfortune, Kakine Teitoku himself appears looking for Rikou. Here they discover that Teitoku is dragging Saiai's injured and unconscious body and tossed it before them. Here, he praises Saiai for making the right decision and having Rikou get away as she is the core of ITEM. Shiage whispers to Rikou to go to take the elevator down and escape. Rikou tries to protest but Shiage is insistent, saying that even if he could get away from ITEM by abandoning her, ITEM would still be destroyed. Teitoku having grown impatient, asks them how long for them to say goodbye, to which Shiage shouts Rikou to go, shoving her into the elevator. However, Rikou maneuver herself in order for her to move Shiage into the elevator. Confused by the sudden action, Shiage falls down to the floor of the elevator. Before he could make a reply, Rikou apologizes to him. She says that she told everyone what he said by the furnace, and continues by saying she doesn't want him to become ash like the corpse. Rikou smiles and tells him not to worry as she is a Level 4 and he is a Level 0, as such she will protect him. Before Shiage could say anything the elevator door closes, and thus Rikou face off against the 2nd-ranked Level 5. Here, she faces Teitoku and tries to manipulate his AIM field, using it as her form of an attack against him by forcibly attempting to make him lose control of his power and go berserk. Her attempt fails however due to her condition in using the Ability Body Crystal and the sheer difference in power between them. As such Rikou falls before Teitoku alongside her comrade Saiai.

When Shiage returns back to Teitoku after deciding to protect Rikou, he finds her collapsed before him. Here, he is surprised by Shiage's return. He tells Shiage that Rikou did well against him despite having no direct battle power. He tells Shiage that she must've used her search power to try to interfere with his AIM dispersion fields to reverse the flow and take control of his power. He then comments on how if Rikou developed more then she could've become the 8th-ranked Level 5. Having none of it, Shiage tries to use his handgun. But there, the Girl in the dress arrives, where Shiage immediately recognizes as the "Crane Woman" from earlier. As Shiage struggles who to aim at, the Girl then says that he should stop whatever he is doing. With those words, Shiage couldn't move his body. Here, the Girl in the dress used her powers on him, to make him not shoot at them because it is seemingly against his nature. Seeing Shiage's struggle, the Girl comments on how he may be fairly kind on the inside. She smiles and then says that her power Measure Heart she can freely regulate "the distance between people's hearts." She advises Shiage to stop fighting against them, as she has him set-up to make it seem that the distance between their hearts are the same between him and Rikou. He can't shoot her just as much he can't shoot Rikou. Seeing this display, Teitoku begins speaking, saying that the situation made it seem like they were the bad guys. He comments on how Shiage and Rikou, a man and a woman, protecting each other is a moving story, and that it is such a rare sight that he feels that he shouldn't destroy it. He then tells him that Rikou will die regardless of what they do, shocking Shiage. Teitoku kicks the Ability Body Crystal case towards him, and says that she was using the Ability Body Crystal to activate her powers. Teitoku then explains the usage of Ability Body Crystal and on how it affects Rikou. Teitoku tells Shiage that Rikou will not last long in her current state, stating that she'll be fine as long as she doesn't user her powers ever again. As Shiage is frozen in shock, Teitoku tells him that they don't need to kill her if she can; use her searching powers and that he doesn't care if she died or not. The Girl then tells Shiage that she collapsed on her own as she kept forcing on using the Ability Body Crystal in order to fight them, and tells him that none of her would be left if they attacked her seriously.

As Shiage stares them down after their revelation, he manages to press the button for the elevator. As Shiage waits for the elevator, Teitoku wonders if he should kill or let her go. The Girl says that they can just leave her alone as a member of ITEM on the edge of her doom can't stop them. Shiage grounds his teeth after what the Girl just said, despite this he still can't attack her. Teitoku says that it'd be easier to kill her, but the Girl counters by saying that since Rikou used his AIM to mess up his Personal Reality, Teitoku should check up on that. She says that his power going out of control would be much more dangerous than Rikou, and that she would rather not die if an ally of hers went out of control. Teitoko becomes annoyed at being bossed around, but acquiesces to the Girl's warnings. He tells her that they should leave as though checking up is easy they don't have the necessary equipment. At that moment an elevator arrives, at which point Teitoku and the Girl leave, allowing Shiage and Rikou to escape harm.

After they leave Shiage checks up on Rikou's condition. She was still unconscious and was in the throngs of a fever, worrying Shiage. Saiai also regains consciousness. She sees Shiage with the collapsed Rikou, and figures out the situation through Shiage's impatient demeanor. She tells Shiage to take Rikou and disappear. Shiage says thank you to Saiai, but she tells him that she didn't say as thanks. She says she was speaking ill of him as she doesn't need useless people like Shiage and Rikou in ITEM, as such she tells him to go out their way. There was a smile on Saiai's lips despite her injuries. Knowing what Saiai actually means, Shiage asks if there is anything she can do for her. Saiai orders him to contact their subordinate organization and call in the information suppression team and an ambulance, as she can't do it herself currently. Shiage complies, and later leaves Saiai.

After leaving, Shiage gets a call from Mugino Shizuri wanting to counterattack SCHOOL and use Rikou again to use her power to track them even if it kills her. Shiage does not follow her orders, trying to find a way to get her as far away from ITEM as she could. While carrying her, Shiage comes upon a bridge where Yomikawa Aiho comes upon them and tells Shiage that although she doesn't know the situation, she'll be taking Rikou with her. Seeing this as an opportunity to allow Rikou to escape from Shizuri, hands her over to Aiho, surprising her. Shiage hastily explains that she has been using Ability Body Crystal, which is slowly killing her. At that moment, a bloodied Shizuri 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 Shizuri, 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.

DRAGON Arc

 * Main article:DRAGON Arc

After leaving ITEM, she is admitted into a hospital for treatment. However, even after being discharged, she is too weak for things beyond ordinary life. Even in that weakened state Rikou sees herself involved in a terrorist hostage situation and in terrorist attacks, and later is faced against Mugino Shizuri.

World War III Arc

 * Main article:World War III Arc

After she and Hamazura Shiage hijack a jet from Academy City in District 23, they arrive in Russia. Later, her condition worsens and she is handed over to a doctor only to find out that she can't be healed with the current technology in Russia. Shiage then tries to hide her whilst fighting against pirates alongside a villager and a soldier.

In the epilogue of volume 22 it was revealed to Shiage, Rikou and Mugino that Rikou is a very valuable test subject who has the potential to be the 8th person to reach level 5. Even more important is that since her power affects an esper's ‘Personal Reality’, it is theorized that Rikou's ability has an incredible potential, such as changing a person’s level or giving a person multiple skills. To put it simply, it would be possible to give Hamazura Shiage the Railgun’s power or demote Mugino Shizuri down to a Level 0. For this reason Rikou was to be retrieved alive while Shiage was not.

Freshmen Arc

 * Main article:Freshmen Arc

After volume 22 she becomes part of the new team "ITEM", which is composed of Shiage, Mugino, Saiai and herself, she has recovered to the point where her health is outside danger as long as she doesn't use Body Crystal, thus she is unable of using her ability. She claims that she still gets "feelings" from her ability from time to time, and decides to follow those "signals" while ITEM decided to play hide and seek with Shiage; this is played comically, though, while her instinct couldn't lead her to Hamazura, she could perfectly and accurately notice when Shiage was "flirting with another girl", regardless on how far they were apart.

Homecoming Arc

 * Main article:Homecoming Arc

Ichihanaran Festival Arc

 * Main article:Ichihanaran Festival Arc

Eve of the Festival
Rikou first appears with Shiage in the lobby of the Hero's Cave, a dentist clinic in School District 7. Here, they wait for Fremea Seivelun to finish her getting surgery after consistantly fails to adhere to Rikou and Shiage's warnings on not drinking hot chocolate before going to bed. As they hear Fremea scream, Shiage asks if there are any other jobs, which has people being paid to scare little girls, to which Rikou voices out her opinion to Shiage.

Later, with Rikou, they accompany Fremea back to their dorm before going home. While Rikou tells him that they need money for some detergent, Shiage laments on how there is no sex appeal to her attitude. His lamentations ends when Rikou finally says that Fremea is gone, much to his irritation. He and Rikou later spend the night trying to find Fremea after learning that she has not returned to her dorm in School District 13.

During the Festival
Rikou accompanies Shiage in finding Fremea. They find her asleep in a bench, unharmed. As Shiage carries her across his back, they meet with Fräulein Kreutune, and nearly attacks them, if not for the fact that she mistook Fremea's identity for Last Order, whom she must now eat in order to fulfill her function.

After Fremea wakes up, and they discover that they are unable to send her back to her own School District, Fremea demands to be fed. For the rest of the scenes, Shiage tries his best to prevent Rikou from punishing after annoying her with her antics. After getting tired, Fremea forced her way towards Shiage's back, forcing him to carry her, annoying them both. Up there, she finds Last Order accompanied by Accelerator and Yoshikawa Kikyou.

Their reunion is cut short as chaos ensues, when Fräulein tries to lunge herself towards Last Order. Fremea, who is still clinging on Shiage's back is thrown down, after Fräulein mows tackles Shiage down to get to Last Order. Fremea and Last Order bear witness to Accelerator attacking her and her invulnerability. As Kakine Teitoku attacks with his Rhinoceros Beetles, Accelerator sends them down the subway tunnel in order for them to escape as he tries to engage in battle with Teitoku. Underground, Last Order talks to Fremea about Fräulein, to which Fremea replies that a lady as kind as her wouldn't hurt Shiage. Yoshikawa Kikyou then gathers attention towards her, and states that Accelerator has bought them time and that whatever issues they might have they need to escape. Shiage agrees, stating just being in the same same place as them could get them smashed into pieces, but adds on how it would be dangerous to support him without a plan. Yoshikawa Kikyou asks if he would if he did, but Shiage just averts his gaze. Just then, the White Beetles come before them. Their appearance shocks Fremea as he was targeted by queer machines before in a tunnel. Her breathing becomes erratic, and her vision becomes blurry. But the attack never comes, a beetle malfunctions in trying to check the order of "Destroying any and all elements that obstruct our mission," due to the presence of Takitsubo Rikou and her AIM Stalker. It is presumed that Rikou used her powers unknowingly.

As he rechecks his orders, he asks his fellow Beetles to assist him. Here, they list down what they think their mission objective is: "to defeat Fräulein Kreutune and eliminate the objective behind her actions, eliminate anyone who would obstruct the battle between Accelerator and Kakine Teitoku, secure the battlefield, eliminate the recent continuing threat to the City by defeating all dangerous elements," and finally, "to protect the residents of the City from all anticipated dangerous elements." However, they then shortly fire at each other, concluding that they, as well as Kakine Teitoku, are "also" dangerous elements in the City. As the beetles attack each other, the sounds of battle make Fremea dizzy. Beetle 05 is then felled, and near Shiage and the others, asking what he was doing, to which Shiage replies not to ask him. It tried to target Last Order again, prompting Fremea to come between him and Last Order. But the malfunction has taken hold, and determined that Last Order and the rest of them are not a threat. Beetle 05 tells them that he will save them in order to protect his order list from a fatal contradiction. Getting back up, Beetle 05 eyes' turn from green to red, indicating that he has indeed been lost from the will of the original Teitoku. Underground in the subway tunnel, the group flees, whilst Beetle 05 holds the other beetles off as long as his strength could bear it. The beetles concentrated their fire on Last Order, for they determined that she was the quickest method in robbing the reason for Fräulein's actions. When they came upon a locked door, and Beetle 05 opened it for them, telling them to go as he fires another shell upon the ceiling, collapsing it upon the other beetles. And when all of them have escaped into another hall, they discovered that the door was too small. However, Beetle 05 paid no attention to this for he did not intend to beat the other beetles in the first place. Beetle 05 slammed into the door, shutting the egress from the other beetles with his body. Shiage questions his judgment, to which Beetle 05 states that it his plan, and that since he has left Kakine Teitoku's conrol, he can no longer renew his Dark Matter, and will break apart. He tells them that the only way to escape from the enemies that can regenerate infinitely is to block their path. But Shiage would not stand for it and demands for him to come as well, but Beetle 05 will not yield. And Shiage could only feel helpless, as Beetle 05 acts as a wall against the other beetles for them. Shiage is later forced by Yoshikawa Kikyou and Takitsubo Rikou to leave. Rikou later notices that Fremea is gone, to which Kikyou also notes that Last Order is lost too. For the rest of the day, Rikou tags along with Shiage, never leaving his side. She brainstorms with Shiage and Kikyou on how to penetrate the Beetles' armor to counter them, stays Shizuiri's hand after she finds out that Shiage lost Fremea, and later accompanies them to the multi-level overpass. She later accompanies Shiage and Kikyou to guide Cendrillon to guide her back to their apartment, as so she can get to her extra body parts to fulfill the mission Kamijou Touma has given her. She later goes with Shiage and Cendrillon and come upon Fräulein Kreutune again. They feed her the candy brain, and successfully fool her function. She later witnesses Fremea and Last Order embracing their friend after the struggles they go went through. It can be assumed that she accompanies Shiage in taking back Fremea back to her own School District and dorm.

Agitate Halation Arc

 * Main article:Agitate Halation Arc

Rikou, alongside Saiai and Shizuri, arrives in the Learning Core during the riots of the "heroes" in order to find Fremea Seivelun. She uses AIM Stalker to search for Fremea during the riot.

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, all of ITEM are alive and well. They are first seen after Touma's heart has finally broken and has decided to kill himself in order to preserve the broken world. Here, they are in a family restaurant, with Frenda arguing with Shizuri regarding her preference with the salmon bento, forcing Shizuri to fire back with a criticism regarding Frenda's preference for canned foods. Saiai comments on how both of them are focused on seafood and that they should make their characters more distinct. Rikou then comments on how they get along surprisingly well. Then Hamazura Shiage, Hattori Hanzou, Komaba Ritoku, and Fremea Seivelun comes along into the restaurant. They are late as Hanzou took them to a shortcut. Saiai asks why they are late and why their efficiency is dropping as they gained more subordinates. Shiage blames Hanzou for the shortcut they took, but Hanzou says it is because Ritoku could not leave a vending machine with a roulette alone. Frenda wonders how Fremea could be so attached to a macho man like him.

St. Germain Arc
The girls of ITEM are in Dianoid's mid-level waiting for Shiage as he still working with Stephanie Gorgeouspalace. Shizuri and Saiai later get into an argument on what to do to pass the time, while Rikou is ignored.

After St. Germain has sealed the Dianoid, Saiai checks the exits and finds that they have been fused. Saiai wonders if it is because celebrities use the top level of the Dianoid as vaults, to which the conversation moves to them discussing about Frenda's own hideout in the Dianoid. As Shiage isn't with them, Shizuri decides to create an escape route using her Meltdowner. Despite firing several times on Dianoid's walls, it simply regenerates. Rikou and Saiai chastises her for continuously repeating her actions. Rikou then asks what they should do next leading to Shizuri to once again continue trying to use her Meltdowner on the Dianoid, much to Saiai's chagrin.

After St. Germain notices Shizuri's incessant attacking of Dianoid, one of them confronts ITEM himself. As he rambles on about his plans, Shizuri orders Saiai to protect Rikou. Shizuri is annoyed by St. Germain's overconfidence, and later vaporizes his arm and the Chambord spear it was holding with her Meltdowner. As people panic at their battle, St. Germain still projects an air confidence despite his missing arm and then later makes a suicide attack on them using a bomb strapped on himself. Despite this, Saiai saves him by tearing the bomb off him and the throwing it away.

As Stephanie Gorgeouspalace is running away from the countless Chambord spears used by the St. Germains, she is later saved by Mugino Shizuri, noting to her that the suicide bomber is still alive. Here, it is shown that ITEM has figured out the people who call themselves St. Germain are somehow being "controlled". Rikou then tells Shizuri to fire a Meltdowner beam toward an atrium, apparently noticing that Shiage was nearby and show to him that they are still alive. They are then attacked by the spears again, but this time they are forced to contend with actually not killing any of them.

While Shizuri and Saiai are fighting the St. Germain, Rikou turns her back on the fighting and ends finding Othinus, believing her to be a high-tech doll. At the same time as this, Stephanie Gorgeouspalace leaves her destroyed Power Lifter, telling Rikou to hide in order to free up Shizuri and Saiai as they would only restrict their movements as they will try to protect them. Stephanie later salvages some parts of her Power Lifter to construct a PDW. Rikou, distracted by what Stephanie was doing, allows Othinus to escape her grasp and leave in an air duct.

Using Shizuri's Meltdowner, ITEM is able to enter the lowest level, where the graviton-style base isolation structure is located. The conversation shifts to Frenda's personality, on how she can easily spill blood but at the same time wash her hands of it and live like a regular girl. Rikou asks what they should do, to which Shizuri says they will deal with whatever is happening and go back home. ITEM then joins, Touma, Shiage, Index, Othinus, Stephanie, and Kanou Shinka in their confrontation against St. Germain.

As the battle begins and St. Germain uses the Chambord spears on them, Shizuri attacks, nearly hitting Shinka in the process. Shiage calls out Shizuri on this. She justifies it as she still believes that Shinka is still in the enemy's side. Shiage notes that Shizuri caused the mess in the first place, referring to her killing Frenda, the person Shinka cared for and the reason that led him into the grasp of St. Germain. Shizuri just sighs and just attacks St. Germain instead. Rikou also arrives with Stephanie and her PDW as she tries protecting Index. With their sides sorted, Shinka declares that he will take back every last piece of Frenda's pride that St. Germain has perverted..

Mugino Shizuri and Kinuhata Saiai assist in the battle using their esper powers, trying to thin down the horde of St. Germain's and their plant matter beasts created through their magic over carbon. During the battle, Shizuri uses her Meltdowner to burn the carbon monoxide that was filling the basement that was being produced by the carbon creatures made by St. Germain. As the battle continues, both Shizuri and Saiai are able to take down several St. Germains though not as much as Stephanie Gorgeouspalace. However, when Shiage moves into Shizuri's line of fire, Rikou uses her powers on her before she could even fire. This surprises Shizuri, but Saiai snaps her back into fighting the St. Germains again. It is shown that ITEM is buying time and providing "samples" for Index and Othinus to figure out a countermeasure against St. Germain. It succeeds, as Index is able to sing a song that slowly unraveled the structure of St. Germain, and later allowed Shinka to put the finishing blow.

After the defeat of St. Germain, and after Saiai and Shizuri leaves Shiage to deal with the problem of the graviton-style base isolation structure, Rikou remains with Shiage. She tries to get close to Shiage but is prevented by Aneri, the AI of Shiage's Power Lifter, making Rikou jealous.

Level Upper Arc
She is asleep throughout the entire conversation the other girls have on whether they should go to a public or private swimming pool as she is asleep. She only wakes up after the sound file to neutralize the Level Upper is also played near the family restaurant they were in.

Sisters Arc
Chronologically, she first appears in Toaru Kagaku no Railgun with the rest of ITEM in order to stop Mikoto from destroying a research facility. She helps Mugino hunt down their target only to become weakened due to the use of the drug, Ability Body Crystal. After Shizuri discovers that they are fighting against Misaka Mikoto, she dismisses both Rikou and Frenda from the research facility. In their mobile base, Frenda becomes worried about her, to which Rikou states it is all right as ITEM is the only place she belongs to. Frenda replies on how it would be nice for Rikou to find something where she can belong to someday, afterwards she then remembers on how she forgot to cleanup her explosives in the facility.

Silent Party Arc
In the anime original arc, they are hired by STUDY under false pretenses, being used as test subjects for their Powered Suits controlled by Diffusion Ghost. For that they desire vengeance for their reputation in the dark side of Academy City. The ITEM liaison gives them information on one of STUDY's factories, destroying several Powered Suits there. Rikou notices Mikoto's presence there but chooses not to divulge that information to Shizuri as she deems her unimportant. They are later present during the Silent Party, taking down several Powered Suits in a stadium, and inadvertently aiding Misaka Mikoto.

Rikou briefly reappears on September 2, while relaxing in ITEM’s private swimming pool together with the other core members of the organization.

AIM Stalker
Takitsubo's Rikou's ability is AIM Stalker (能力追跡 (AIMストーカー) ), which she uses to record other espers' AIM field and track them down. Rikou herself boasts that as long as she recorded their AIM dispersion fields she can track them down even if they were to leave the solar system. The ability also allows Rikou to accurately gauge the distance and direction of the target, as exemplified by Shizuri utilizing it to hunt down Mikoto from a safe distance. So useful is her ability in ITEM that she is essentially its core, much more than Mugino Shizuri who is a Level 5.

Initially, she required the consumption of the Ability Body Crystal to use her powers, as it was one of those abilities that can apparently be used when she is overloaded. Her continued use however have worn her body down to the point where she will collapse and become seriously ill if she uses it again. What's worse is that it can also be fatal. Under the effects of the Ability Body Crystal her eyes widen and enable to use her power. However, prolonged usage of her power eventually tires her out. During the events of World War III, she was eventually healed Elizalina when she and Shiage managed to escape into the Elizalina Alliance of Independent Nations. She would then later use the powers on Mugino Shizuri, and later be able to search espers with the ability, an example when she searched for Fremea.

Potential
Her ability allows her to become the 8th-ranked Level 5 due to the massive potential it has, overturning the idea that there could only be seven Level 5s. Both Shizuri and Teitoku have stated that her ability can take control of their powers through reversing the flow of their AIM dispersion fields. Shizuri further speculates that she could strengthen espers and send them out of control if she wanted.

During World War III Rikou was able use her ability to help Shizuri's erratic Personal Reality with Meltdowner and in turn, that move was used to save Shiage's life. Much later, During the Ichihanaran Festival as Teitoku he loses control of the Dark Matter due to Beetle 05 rebelling against him, and now was no longer being recognized as the originator he recalls on Takitsubo Rikou presence in the group when he attacked them for the first time. He also recalls the information on her ability and that she also had the possibility of using others’ AIM diffusion fields to distort their Personal Realities. He then theorized that she might have, either consciously or subconsciously, incited the change in Beetle 05. This seemingly backed up when Kihara Yuiitsu comments on Takitsubo Rikou's progress, referring to it as going "exceeding well" tagging her interest with her as gold.

Knowing her potential researchers have speculated that if she becomes the 8th-ranked Level 5, her AIM dispersion field would be able to use as an intermediary to freely control other espers' Personal Realities, beyond Shizuri's speculation. As Personal Realities were the source from which espers powers and phenomenon were brought into the real world, controlling it would not only mean increasing or decreasing an esper's level, it would also mean she could give different kinds of powers to anyone, switch powers between espers, or remove esper powers all together. For example: Hamazura Shiage would be given the Meltdowner while Mugino Shizuri would be brought down to being a Level 0. Moreover, Dual Skill a previously impossible phenomena would become reality. Furthermore, she can do it freely at any place she wanted to. According to the ITEM liaison, if Rikou's potential is realized she alone could out every function that Academy City does, practically making the Power Curriculum Program obsolete.

The problem with Rikou was though she had a rare potential, getting her to "bloom" was difficult. Hence the reason for the Ability Body Crystal, apparently to force her to show her potential through overloading her ability, though even this wasn't enough. During the course of the series, her relationship with Shiage and the struggles she had to face with him has opened up the path to her realizing her full potential as the 8th-ranked Level 5.

Design evolution
Rikou's overall design remained the same for most of the series, having larger eyes and bigger heads as Haimura's style evolved. Rikou was designed to have the least presence amongst her colleagues.

Quotes

 * (To Frenda talking about ITEM, from Railgun Chapter 30) : "I'm fine... This is the only place where I belong, after all..."
 * (To Shiage, Vol 15) : “I told everyone about what you said by the furnace. I don’t want you to become ash like that. Don’t worry. I’m a Level 4 and you’re a Level 0. So I’ll protect you, Hamazura.”
 * (To Shiage, Vol 21) : “It’s okay, Hamazura,” -- “Even now, you’re fighting to protect me. So you aren’t pathetic.”
 * (To Shiage, NT1) : "…Don’t NTR anyhow, Hamazura, you’re mine" (NTR is a "genre" within the visual novel world were a lover is stolen away by another person).
 * (Sensing Shiage's actions, NT1): “…A signal is coming from north-north-east… I sense that Hamazura is flirting with another girl…!!”
 * (To Shiage, NT2) : “…Kinuhata always says you’re super Hamazura-y, but I’m a little disappointed that it’s at the level of a wild beast…” -- When Rikou found Fremea and Hamazura on what she perceived as a unsightly position.

Trivia

 * Rikou cannot swim, though she can float.