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. After constant use of the Ability Body Crystal, and the dark turn their leader Mugino Shizuri takes, she becomes estranged from the group, and later flees and falls in love with Hamazura Shiage.

The group later reforms after the conclusion of World War III, and all now live in a single apartment.

Appearance
Rikou is usually seen wearing her pink sports outfit, so much so that Hamazura Shiage stated that she would probably wear it to a wedding or funeral. She also has deceptively large breasts underneath her sports shirt. Rikou has been described as someone who chooses clothes based on functionality and not on appearance, similar to Yomikawa Aiho.

Personality
Rikou's personality resembles that of Aisa, in that she is rather blunt and rarely expresses her inner-thoughts. Despite the fact that she shows little emotion, she does care about her fellow 'ITEM' members and in particular, Shiage, whom she is in love with. Even with her friends she would normally behave quite cold and detached but not in a bad way, she has been described as "lethargic" instead of stern or aloof.

Whenever a character has been put in a ridiculous position she usually address him/her with encouraging lines such as "Don't worry. It's ok, I'll support you", though her courtesy and condescending behavior will probably have the opposite effect and would bring a heavy blow to whoever she was trying to cheer up.

It should be noted that Rikou as shown a selfless side of herself several times, 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 also partly because of that selflessness that Hamazura Shiage wants to "bring happiness" to Rikou if possible.

As of New Testament, Rikou has developed a very possessive personality towards Hamazura and reacts strongly towards any sign of unfaithful behavior, to the point where Hamazura described that attitude as "a dangerous light in her eyes". It should be noted that Rikou has shown jealousy even in situations where Hamazura himself refutes that nothing can possibly be happening (for example, when Fremea was innocently sleeping on Hamazura's lap ).

Battle Royale Arc

 * Main article:Battle Royale Arc

Out of all of the ITEM members she is the only one to treat Shiage with kindness, which ultimately leads to their relationship. At one point, she meets with Hamazura while he is disposing of a corpse in a furnace, and she asks what is wrong. However, he ignores her and says outloud about what a person's life is and when did Level 0's lives become a cheap thing. When SCHOOL finds one of ITEM's hideouts, Rikou knows the SCHOOL is likely after her due to her ability. Hamazura initially tries to get her into an elevator while he distracts Kakine, but she manages to push Hamazura into the elevator instead because she did not want him to die. She tells Hamazura that she does not want him to become ash which has a great affect on him.

In her fight against Kakine Teitoku in vol.15, she tries to manipulate his AIM field and use it in the form of an attack against him, forcibly attempting to make him lose control of his power and go berserk. This fails however, and due to her condition and the difference in their power, she still loses. However, when Hamazura returns, Kakine chooses to simply spare her life since if she forces herself to use her powers too many more times she will die, but she might be okay if she does not use her power anymore.

Mugino initially plans to force her to use Body Crystal again to find the members of SCHOOL, but Hamazura defies her and runs away with Rikou. Along the way, they run into Aiho Yomikawa and Hamazura begs her to take them somewhere safe. Before they could leave, they see Mugino with half of Frenda's body. Hamazura manages to convince Yomikawa to take Rikou away from the area while he kept Mugino busy.

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 Hamazura 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 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 objectivbe behind her actions, elimate 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 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 mult-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.

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, Body Crystal.

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.

Abilities
Rikou's ability is AIM Stalker (能力追跡 (AIMストーカー) ), which she uses to memorize other espers' AIM field and track them down. To use this power she needs to consume what is known as Body Crystal, and in recent chapters, continued use of the drug has worn her body down to the point where she will collapse and become seriously ill if she uses it again. Rikou developed in such a way that she can only use her ability by consuming this drug, as part of an earlier project to create a Level 6 before the "Experiment" involving Accelerator, and thus she can no longer develop through the normal methods other espers go through.

She states that her ability allows her to steal other espers' abilities by memorizing their AIM field, potentially allowing her to become the eighth Level 5 esper in Academy City. This fact is also mockingly mentioned by Kakine Teitoku after their fight, who states what a shame it is that she has to rely on a drug to use her powers.

Due to over-use of Body Crystal, the poison in her body makes it such that she will self-destruct if she uses her ability any more. This problem was eventually healed by Elizarina when she and Shiage managed to escape from Academy City.

Near the end of World War III she manages to use her ability to help Mugino's currently erratic Personal Reality with Meltdowner and in turn, that move was used to save Shiage's life. This reinforces Academy City's view that Rikou can affect other espers' Personal Reality, according to ITEM's liaison on the Board of Directors.

It's noted by ITEM's liaison that upon reaching Level 5 Rikou's ability could theoretically have the potential to give and take esper abilities of any level on a whim and at any range, essentially allowing her to completely recreate or undo Academy City's work on espers. For example; Shizuri, a Level 5, could be reduced to a Level 0 by her while she could also make Shiage, a Level 0, into a Level 5. She could potentially even create espers with multiple abilities or a whole group of Level 5s on a simple whim. This potential makes her even more valuable in the eyes of Academy City than even one of their Level 5s.

During the Ichihanaran Festival as Teitoku he loses control of the Dark Matter due too Beetle 05 rebelling ageist 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.

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.

Quote

 * (To Frenda in the Railgun manga, talking about ITEM) : "I'm fine... This is the only place where I belong, after all..."
 * (To Hamazura, 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 Hamazura, Vol 21) : “It’s okay, Hamazura,” -- “Even now, you’re fighting to protect me. So you aren’t pathetic.”
 * (To Hamazura, 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 Hamazura's actions, NT1): “…A signal is coming from north-north-east… I sense that Hamazura is flirting with another girl…!!”
 * (To Hamazura, 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.
 * Rikou can fall asleep with her eyes open.
 * It is discreetly implied that Rikou might be a Child Error.