Unlike Rensa #29, she is more soft-spoken and nearly expressionless. She is the first Rensa operator to be introduced in the series.
- Main article:Rensa#Appearance
Rensa #28 wears the nurse clothing that is standard for the cyborg. It is pink and backless to accommodate the large AIM receptor that comes out of her back. Over this outfit is a purple cardigan. Unlike Rensa #29, she has her long dark hair worn up to keep it tidy, her fingernails were cut short with no manicure, and her other outward characteristics were just as focused on being hygienic. This made her look very plain, but the look in her eyes was anything but plain, as it however looks like her eyes showed that she did the opposite of "save" lives.
Rensa #28's personality very much in stark contrast to Rensa #29. Her demeanor is that of a rational-thinking and soft-spoken nurse, having robotic mannerisms, talking about the "targets" and the "objectives" while being rather submissive. She is nearly expressionless most of the time, though that doesn't mean she has no emotions, as Kuroyoru Umidori can attest, she can form a thin but cruel smile on her countenance. She is also capable of striking psychological fear into the her enemy if she needs to.
She has absolute loyalty to Yakumi Hisako, though she tries to advise her on things such as telling her of errors in her experiment, or rational stylistic choices for her camouflage skin, she is unwilling go back on her order. She has been shown willing to go alone in a the Critical Pathogen Specimen Freezer of Yakumi Hisako's Hospital in order to protect Hisako and defeat an upcoming enemy despite the lack of information. As an extension to this, she always calls her Doctor.
She also has an odd habit of assigning odd nick names to people and places such as: I am fat because of a fried chicken conspiracy-chan, Clean-Freak Princess for patients at the hospital and Sticky Freezer for the Critical Pathogen Specimen Freezer, much to Hisako's chagrin.
One interesting part of her personality is that she is interested in rare powers, and as she can copy any esper ability, she has shown disappointment in killing an owner of rare power, as with the case of Rensa #28 copying Kamijou Touma's Imagine Breaker.
How she had come to be reduced as a hypothalamus to pilot the Rensa cyborg is not known, though according to Rensa #29's own opinion based on her own experiences, she may have been saved by Hisako from a difficult situation in which they are either grateful or willing enough to have their hypothalamus removed from their body for use as the Rensa's operator.
Rensa #28 acts as a nurse in Yakumi Hisako's Hospital and assistant to Hisako herself, whom have her assist her in her plans with the Agitate Halation Project.
Shinyaku Toaru Majutsu no IndexEdit
Agitate Halation ArcEdit
- Main article: Agitate Halation Arc
She is first seen talking with Hisako. The latter, Hisako warns that the perpetrator may be unpredictable but Rensa keeps on reinstating that she will exterminate the intruder. Hisako then realizes that the enemy might have wanted to see which rooms went online first, allowing the intruder to bypass the labyrinthine structure of the hospital and the hidden rooms. Rensa determines that there has been an intrusion of the Critical Pathogen Specimen Freezer, to which Hisako agrees and believes that she should be evacuating just to be safe. It is unknown if she was even aware that Tsuchimikado Motoharu attacked Hisako in order to gain information from her.
Hisako later laughs at how she survived in the "billiards game" that is the Agitate Halation Project, and notes that since she survived it means that the project is within the acceptable margins of error, disregarding Rensa's reports. After going through their "patients", Hisako tells Rensa to begin the final phase of their plan. Already finding where Fremea is located, she will be the leverage point, while Kuroyoru Umidori will be forced into being the counterbalance.
With that, she and Hisako go to School District 13 to start the operation themselves. Using her powers, she later takes over Beetle 05's Dark Matter in order to draw Fremea Seivelun out of her dormitory. Rensa #28 appears before Umidori in a back alley somewhere near Fremea Seivelun's dormitory. There, she meets both Umidori and Fremea. She tells Umidori that she will collect the "money" later, and had her sights upon Fremea, and spoke of capturing her as the primary objective. Despite having no obligation to protect Fremea, Umidori spoke to Rensa, and says her jests are terrible, and that she should've not underestimated Freshmen, as she told Rensa that she assumed that trust was more important to Umidori than money. Umidori blankly tells her that she will kill her, but Rensa simply smiles and says that the situation is progressing well. Rensa states that the artificial protection target (Fremea) has enough control over her enemy to create a dark hero (Umidori). Umidori doesn't understand, but Rensa reveals to her that the Freshmen were created only to input fear, anger, and joy into Fremea Seivelun's mind, something designed to fail, and have played their role perfecty. Umidori is not amused by her revelation and finally charged towards her, drawing her eyes to her right hand in order to hide the fact that she will pierce her with a nitrogen spear using the left. Umidori moved to strike her down and behead her, but her nitrogen spear was extinguished at an instant, much to her shock. Rensa had used her own nitrogen spear. Rensa continues to speak of Umidori's position as a dark hero, and speaks of plans of using her against a normal hero.
Angered, Umidori moved to strike again and dodged Rensa's strike, and as she lost her balance, Umidori tried to attack her with both of her palms. Before she can do so however, Rensa reveals that she is a cyborg, and a plate from her back reveals a queer contraption resembling a large mechanical flower growing out of her. A sense of foreboding pervades Umidori, as metallic noises ring out and the flower is inserted back into Rensa. And then, Umidori continues with her two palmed attack, but they are immediately burst and cause a large explosion as it touched Rensa. It was the power of Accelerator, that allowed her to it, and Umidori accurately analyzed that it was beyond something like the Five OVER series. Once again, the flower appears from her back, and as if preparing new ammunition, strange noises began to emanate from inside her. Umidori could only watch after being knocked down as Rensa turned her back on her and pure white wings began sprouting from her back. It was the power of Dark Matter, and Umidori assumed that the flower rearranged Rensa's interior. Predicting that she might have more than just two and the apparent danger before her, Umidori upped the output of her spears and swung her arms around like they were boosters and then jumped straight into the air, making her way up to the roof. Once again she hears that queer metallic noise, and Rensa told her that she was created to have the power needed to defeat all seven Level 5s on her own, and mocks her attempts at escape. Then, Umidori heard the clink of a coin, and she knew that she would fire Railgun. Umidori is then caught in the destruction.
After Kinuhata Saiai forced Hamazura Shiage to find Fremea in order for her to deal with Hisako and her army of man-eating roaches. Umidori apparently continued to battle against Rensa in the rooftop until she is thrown down to the ground, where Shiage comes upon her. As Shiage tries to go towards her, Rensa appears before him. She refers to Shiage as a low level problem, and that it would be difficult to convince him that Umidori is her enemy. She concludes that Shiage is expendable to the experiment, and prepares to attack him. Umidori, unable to speak, hastily writes down that Rensa is a cyborg, a more advanced one. Suddenly, Rensa's back opens up and a large mechanical flower opens up from it, performs some sort of calculation, and then folds back within her again. She then fires a nitrogen spear, and Shiage immediately concludes that she can copy esper powers, and that she can construct output points similar to Umidori using her mechanical arms. However, that is not the only thing she can do, as she boasts that she can freely switch through all Level 5's powers other than the 7th ranked, and any esper within 200 meters. Rensa relates on how she will kill him to fix the error and then continue as planned to have Umidori framed for killing Fremea. After some pondering, Shiage is still confused on why the assassins would go out of their way to try to kill Fremea in such a massive scale and frame it on Umidori. Moreover, he ponders on why she hasn't killed the both of them yet, and concludes that Rensa wants them to run away in order for them to draw out Fremea for her. Seeing the cyborg, Shiage assumes that Rensa has to hold back in order for her not to accidentally kill them. Whispering to Umidori, Shiage says that he will charge at Rensa, making her falter and block her vision. Shiage tells Umidori that she needs to stab a spear from behind him, even if she needs to stab it through his body so long it won't kill him. Shiage's plan is under the assumption that she will not use Accelerator's redirection for them to stay alive and escape.
With that, Shiage begins charging towards her. However, though Umidori is impressed by Shiage's bravery, she realizes the absurdity of the plan working under their circumstances, and has come to conclude that Shiage will be abandoning her in order for them to destroy each other. Wanting none of that, she determines that she will kill Rensa but not for Shiage. She does nothing as Shiage charges towards Rensa who prepares to use her arsenal of powers. By the time she realized the truth, it was too late. Shiage is struck down by hundreds of wings of Dark Matter, though not killing him as Rensa has intended. There, Umidori screams due to her feelings. Seeing as Shiage is injured, he cannot lead Rensa to Fremea, therefore, she concludes that she will kill him and use another acquaintance to find Fremea Seivelun instead. While on the ground, Shiage apologizes for not working harder in gaining her trust, making Umidori feel guilty. As Rensa prepares for the killing blow, Shiage tells Umidori to abandon him, as Rensa needs her alive to frame her for Fremea's killing. He suggests asking help from ITEM before Rensa get the chance to use them to find Fremea. But Umidori can only drown in her own guilt, blaming herself for the doom Shiage will have to pay in her stead. Suddenly, Kamijou Touma finally arrives and prevents her from killing him.
Thinking Touma would be easy, Rensa #28 did not turn around, and instead once again called up her mechanical power in order to use Kakine Teitoku's Dark Matter. Her Dark Matter wings tried to pierce Touma, but he simply negates this. Realizing this, she tries to turn around but Touma simply kicks her down before she can do so. There, Shiage warns Touma that it can use multiple abilities and even several of the Level 5s abilities, shocking Touma. Rensa then turns around and calls upon a Meltdowner beam, though Touma simply crouches out of the way. Rensa #28 becomes frustrated at the events unfolding, calling Touma a mid-level problem. Then, Touma asks if she is the one that made Tsuchimikado Motoharu go through such lengths (effect of Agitate Halation), and the one who was targeting Tsuchimikado Maika. Rensa says that Motoharu attacked first and states that it is only fair to pay Motoharu 100-fold for it, angering Touma. Rensa tries to use Mikoto's ability on him, but he simply negates it again, shocking Rensa, and declares that she will now kill Touma to correct the course of the plan. Rensa then uses Accelerator's power to call up 120 m/s winds, but Touma is able to reach her before she can attack him with it and gets her face punched for her trouble, though she blocked it, stopping her control of the winds. She then tries to use Railgun on Touma. As she picks up a coin using magnetism and tries to shoot her Railgun, Touma punches her hand to throw off her aim, missing him. 
There, Touma mocks her for her poor copies of the Level 5's abilities, and tells her that due to the lag between switching her powers, he can read her timing. Touma headbutts her, and she staggers backwards near a dumpster, which she promptly peruses after calling her mechanical flower again in order to use Shokuhou Misaki's Mental Out ability. Finding a remote to focus her ability, Touma immediately kicks it away from her. There, he continues to mock her, stating that she may have the abilities of a Level 5, but she isn't a Level 5 herself. Rensa calls upon Meltdowner again, evading it and in response punches her dead center in her face. However, Touma immediately notices how clean his attack is and realizes that it a trap. Using her mechanical body, she raises Touma up with a single hand by his neck. She declares on how he was only supposed to defeat Tsuchimikado Motoharu, and expresses her confusion on how he is still interfering in the Agitate Halation Project despite completing that goal, but tells him will end now. Touma laughs on how she doesn't get it, that despite controlling people like in a game of billiards, they don’t need some giant project as all it takes is someone saying "help," and he and other people will act. Rensa #28 coldly tells her that his words are meaningless and will put no more effort in analyzing them. There, she tells him that he will reverse his bloodflow using Accelerator's ability.
However, she hesitates for a moment after checking Touma's profile in the Bank, believing that he has a rare power, and that she will not be able to use it now as Touma will now be dead. Despite her personal opinion, Rensa #28 decides to kill Touma with Accelerator's ability. However, she then notices Umidori attempting to attack again. Seeing this as an opportunity to use Touma's power, she calls upon her mechanical flower again to knit her insides. Surprisingly, Imagine Breaker flowed into her right hand before it was overwhelmed by it, making her arm swell like a balloon, and giving errors to her cyborg body. A fatal encounter in her operation is detected without Rensa being able to determine why the Imagine Breaker caused an error in her. Her right arm explodes and she shuts down.
Touma, Shiage, and Umidori later leave Rensa alone in the back alley, not knowing what to do with her. Rensa later reboots and is visited by Yakumi Hisako who now transferred her consciousness into the AIM diffusion fields using the Shading Computer. Hisako tells her to stop being naked, and though Rensa suggests that her current look would make her more intimidating, she is forced to do so. After Rensa changed her skin to look like a cloth, Rensa tries to find where Hisako is talking to her but could not find her. Hisako tells her there is nothing wrong with any of her sensory organs as there is no way anyone can see her now in her current form. Hisako tells her on how she has disposed her body safely, and that her consciousness has been transferred to the shading computer that uses the AIM diffusion fields as a medium, becoming an AIM thought being. This surprises even Rensa, believing that the project was meant to destroy the heroes of Academy City. Hisako tells her that it was all just a ruse to hide it from the Board of Directors, and that she has now stepped into the realm of Hyouka and DRAGON (Aiwass), and that she should be able to make significant advances in her research. Hearing this, Rensa is glad and asks if she should fall back now that she has achieved her objective. Hisako however, tells that she wants to go beyond the AIM diffusion fields of the city that is used by Shading Computer, and dreams of using a different medium (a fluid) such as the winds or seas of the world, touching infinity so to speak. Rensa asks if it can really be applied to the fluids like air or water, as the reason why AIM diffusion fields was chosen as the Shading Computer's medium as it can control the students who influence each other through the AIM diffusion fields. Hisako states that it can, as humans can be influenced by the concentration of oxygen in their blood and slight adjustments in atmospheric pressure. She says that she can simply work herself into the middle of that. Rensa asks what she requires in order to shift into another medium, and Hisako responds that she needs to kill Fremea Seivelun in order to free her from the AIM diffusion fields of Academy City. Then, a vehicle arrives containing her spare parts, and asks what she has in her disposal. Hisako tells her that she can use anything but the roaches, as their guidance substance was taken they were probably gathered in once place and destroyed. Here, Rensa #28 apparently decides to switch with Rensa #29 before she begins the final phase of the plan in the Learning Core.
After the end of the arc, Touma later gathers all the hypothalami of the Rensa's found in Yakumi Hisako's hospital. He intends to put them in cold storage until the time technology has advanced enough to find a way for them to be truly saved.
- Main article:Rensa#Abilities and specifications
As she operates the Rensa cyborg body, designed specifically as a countermeasure in case the Level 5 Espers would turn against Academy City, she is capable of using the abilities of any esper within a 200 meter radius, using a flower-like device that protrudes from her back with "knitting needle"-like device within the flower. These knitting needles would then proceed to calculate and imitate the values of different Esper powers allowing her to be capable of using the abilities of the #1 up to #6 Level 5 Espers, which is a default set part of her.
Unlike Rensa #29, she prefers using projectile attacks unless her defense falls behind a certain point. This, combined with the lag between switching powers makes a fatal combination against Rensa if an opponent is capable of reading and utilizing such idiosyncrasies, opponents like Kamijou Touma. Moreover, it has been noted that due to her though patterns created to kill the seven Level 5s, her strategy may have been to respond with the same power as her opponent when she is unsure what to do.
Character Art DesignsEdit
Finally, continuing with the plant motif that is apparent in some of Haimura's art such as Aleister Crowley's Blasting Rod, he had designed Rensa's AIM reception design with the thought of combining a cosmos flower and a parabolic antenna.
- (To Yakumi Hisako regarding patient reports, from NT7): "I have the test results for Mr. Gerascophobia. I also have the treatment schedule for "I am fat because of a fried chicken conspiracy"-chan and a complaint to the hospital from the Clean-Freak Princess. Please look over it all."
- (To Yakumi Hisako regarding an attacker in their hospital, ibid): "I shall exterminate them."
- (Rensa #28 after taking in Imagine Breaker, ibid): "Dh...gh...What!? High level problem detec-... I-I-Imagine Breaker should be nothing more than the power to negate other powers. Why is it causing such great destruction...just from being drawn into me!?"
- ↑ 1.0 1.1 1.2 1.3 Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Chapter 3 Part 4
- ↑ 2.0 2.1 Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Chapter 3 Part 7
- ↑ 3.0 3.1 Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Between the lines 2
- ↑ 4.0 4.1 Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Chapter 4 Part 1
- ↑ 5.0 5.1 5.2 Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Chapter 2 Part 8
- ↑ 6.0 6.1 Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Chapter 3 Part 11
- ↑ Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Chapter 4 Part 12
- ↑ 8.0 8.1 Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Chapter 3 Part 8
- ↑ Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Chapter 3 Part 9
- ↑ 10.0 10.1 10.2 Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Chapter 3 Part 10
- ↑ Shinyaku Toaru Majutsu no Index Light Novel Volume 07 Epilogue
- ↑ 12.0 12.1 Rainbow Spectrum
|Kihara Nayuta||Kuroyoru Umidori||Mugino Shizuri|
|Kihara Gensei||Rensa 28||Rensa 29|
|Silvercross Alpha||Kuriba Ryouko||Salome|