Kihara Yuiitsu

Kihara Yuiitsu (木原唯一) is a character introduced in Shiyaku Toaru Majutsu no Index. She is a member of the Kihara family who appears at the end of Academy City's attack on Baggage City.

Etymology
As part of an apparent trend to the Kihara family having names related to science or mathematics, Kihara Yuiitsu's given name (唯一) can be translated as "Single", "Sole", "Only", and "Unique".

Appearance
Yuiitsu is a young woman of an unspecified age who wears a ready-made cheap suit, making her look like she's going to a job interview.

Personality
Like all Kiharas, she has the tendency to do actions in the most evil way possible and has the natural aptitude towards science and experimentation. She uses people for her own needs in experiments, as what she did to Yakumi Hisako of the Academy City Board of Directors, who apparently became the hapless recipient of her intellectual curiosity. She apparently has the tendency to lose motivation in things if she is unable to find something of interest in it, and most likely easily overlook things that can be seen if properly analyzed, as with her conversation with Kihara Noukan seems to imply.

She greatly admires Kihara Noukan, even calling him "sensei" and reverentially bowing to see him off, though sometimes treats him like an actual pet dog.

Background
Due to the fact that Freshmen was set up to specifically input the values required to make Fremea Seivelun the bearer of Agitate Halation, Yuiitsu apparently had implanted her intellectual curiosity into Yakumi Hisako without her knowing in the same vein as the Dark May Project, combined with Hisako's field of expertise led to the Agitate Halation Project. Apparently, it was for the simple fact to make her a subject of her experiments. She later meets Hisako personally herself, and due to inserting her personality into her, got along well.

She apparently has enough political power and know-how to be the one to negotiate with the Baggage City leadership, and under favorable conditions to Academy City.

Baggage City Arc
Yuiitsu is sent by Academy City to Baggage City with very sensitive, top-secret documents and to negotiate with the now decimated Anti-Academy City Science Guardians. She speaks with an old man who sets the Guardians' policies and forces his hand by demonstrating that it would be best to end the conflict now, while negotiating she uses that argument that if Academy City were to weaken and no longer be the capital of the Science side, the Kihara Family would spread throughout the world, a fact that terrorizes the old man. He agrees to sign the papers Yuiitsu brought with her, which ends Baggage City's involvement in the conflict against Academy City.

Eve of the Festival
Yuiitsu goes to a secret underground laboratory beneath School District 3, where Kakine Teitoku is apparently still alive and is sealed in a giant room covered in a silkworm cocoon-like substance. There, she explains to Kakine the situation with Fräulein Kreutune and asks for his help with the situation. She understood that Kakine would likely cause chaos and destruction, but since she is a Kihara, it doesn't matter to her. Thus, Yuiitsu lets him loose in Academy City, interested in her research between the difference of the two top ranked Level 5s, Accelerator who ruled over destruction, and Teitoku who ruled over production. A comparison she finds somewhat intriguing because she felt like she could see some truth about the essence of science in that fact.

Day of the Festival
For the most of the arc Yuiitsu monitors in the mission Kakine Teitoku was supposed to take. Although, she seems quite fine and even intrigued by the events that unfold.

Teitoku first contacts her after he finds Fräulein Kreutune. Teitoku tells her that he wants to the mission his own way, to which she agrees, saying that Teitoku should smash the worst case hypothesis the Kiharas have come up with. She concludes that the destruction he is going to cause will sure to have a wonderful meaning to science.

It is unknown on how much activities she could monitor. Nevertheless, she was several things that have occurred during the arc. She was aware of Teitoku's White Beetles' differing interpretations of Teitoku's oral command. She comments on how it is like a form of narrowing down ideas, and while saying that it is not good, an expression of pure enjoyment falls upon her face.

At the end of the events, Yuiitsu hung out inside the facility that held Teitoku. Alone, she takes a voice recorder to comment on the things that have happened. She states that the Dark Matter has cleanly disappeared, and have requested examinations to take samples on the surface of 40 different locations, though doubts if anything will come out of it. She then pulls out a devices that can connect to the City's SNSs and message boards. She comments how there urban legends regarding Teitoku, and that someone from the dark side of Academy City is spreading those rumors. She then tags it yellow. She then comments on Accelerator's development, stating that even though malice was injected within him, it is not clear if it will bloom into anything, stating that it would be a waste if he remained as he is. She adds that it would be nice if he could become something more grotesque with his wings.

She comments on Takitsubo Rikou's progress, referring to it as going "exceeding well," tagging her interest with her as gold. On Fremea Seivelun, she comments on how that her esper power, Agitate Halation, is confirmed to have been used unintentionally. She tags her interest with her as platinum, remarking on how one must be extremely careful when gathering data.

She then turns off her voice recorder, but switched it back on after gathering her thoughts. She comments that with Fräulein Kreutune, it is out of her jurisdiction. She states that she is rather unhappy with it, but from what she has observed, she has a durable body that can't be killed no matter what, a heart that desires friends, and the possibility of being controlled regardless of her personal beliefs. This leads her to conclude that she is very similar to Kazakiri Hyouka, and references that it connects a single thread from Fräulein, Hyouka, and Aiwass. She states that she may be over thinking in including Aleister Crowley into this connection as well, supposing that she can draw the line between the chairman and Aiwass.

Finally, after switching on and off her recorder a few times, Yuiitsu finally comments on the intruders in Academy City, the magicians. She states that there are similarities that have been identified that are similar to the ones that was witnessed in World War III and Baggage City, but says that it too is also outside of her jurisdiction, and says she will leave it to somebody else. Her words trail and becomes silent. She then sighs and lets go of her voice regarding falling to the floor and getting crushed by her foot. She then strangely lets out a voice that says that what she is doing isn't Kihara-like at all, a phrase that was once often used by Kihara Enshuu.

Agitate Halation Arc
It is implied that she is the Kihara who Rensa references to have given the report regarding Fremea's progress, likely about the Agitate Halation.

For the most part of the events of the "heroes" rioting in Academy City, Yuiitsu acts as an observant, though predicting that the experiment will fail. After the Agitate Halation Project's failure, Kihara Yuiitsu and Kihara Noukan apparently influenced the "heroes" to stop rioting after the defeat of Rensa and Yakumi Hisako. She is seen with Kihara Noukan walking in a park in School District 13 the morning after the incident. She commends Hisako for being a nice patron to her despite the failure of the project, to which Noukan replies that she may have been playing around too much. Noukan mentions on how Yuiitsu managed to implant her intellectual curiosity with Hisako but not being able to make Hisako to understand how a Kihara thinks. Yuiitsu laughs, recalling on how Hisako wondered on how they got along so well, and commended her for being useful to her research. Noukan however states that she went too far, but Yuiitsu says that she has learned her lesson.

Noukan then tells Yuiitsu of the top 3 likely candidates to become board of directors as insurance for her plans. But Yuiitsu simply vetoes it, saying that it isn't Kihara-like, prompting Noukan to ask of her plans. Yuiitsu then mentions the use of the Shadow Ruler plan, apparently an organization, to which Noukan throws doubts at such a convenience that she can use. Yuiitsu states that they will take action if they make them think there is a reason to take action, pointing out Academy City, the city of science, and its strange relationship with jinxes and urban legends. She says that she can manipulate a bit of information to make certain facts seem true, which will prompt them to action in lines with her schemes, mentioning the M-Fund and the UFO Investigation Committee as examples. She then asks Noukan to start deceiving important people. Hearing this, Noukan acquiesces to her plans, stating that he can give two or three people she could use in her plan, rich social climbers that are dumb enough to be manipulated by her. Hearing this Yuiitsu thanks to him as always.

With the Agitate Halation dead, Yuiitsu then asks what they should do about it. Noukan states he has no particular interest in but tells her that it might not be a failure. Noukan states that the Level 5s of Academy City gathered in one place despite Hisako's wishes, as well as Kamijou Touma's appearance of his own free will despite the Imagine Breaker negating any influence from Agitate Halation. He tells Yuiitsu that even though the experiment ended in failure, perhaps Agitate Halation was simply too much for her to handle, and that there may still be something of interest. Yuiitsu agrees with his analysis, to which Noukan states that she never shows any motivation if he is not the one keeping score for her.

Lance of Gungnir Arc
For reasons unknown, Kihara Yuiitsu insists to Amano Kaguya to use the S5 cannon on the Hikoboshi II to deliver Accelerator, the cargo of said cannon, to Denmark, where he is supposed to kill Kamijou Touma and Othinus. Kaguya says to Kumokawa Seria who had come to visit her that she supposes that she should keep it a secret from Accelerator.

Mental Out Arc
She is first seen with Kihara Noukan in a pet cafe, trying to eat a puppy cake, much to Noukan's chagrin. Having enough of Yuiitsu's teasing, Noukan demands her to get to the point. Yuiitsu tells Noukan that Shokuhou Misaki has noticed the manipulations done by Mitsuari Ayu. Moreover, Yuiitsu tells Noukan that Ayu has begun moving as well, taking over her entire section from within for her use after Misaki noticed. Their conversation later devolves into referring Mitsuari as an "ant" in reference to her name in kanji having of ant in it, and comparing her to the samurai ant. Yuiitsu then laughs as the prospect of Noukan's "work" becoming more violent. Noukan then says that he isn't fond of Yuiitsu's tendency for destruction and says that he dislikes unnecessary destruction, adding that what he is saying is more about his likes and dislikes instead of good and evil. Yuiitsu replies that he doesn't really get him and then pouts. She tells Noukan that what he said means that he is willing to sacrifice millions of people as long as it is necessary, and asks how it is any different from her or any Kihara. Noukan says that it is an issue of likes and dislikes, and scenarios like the one she presented cannot be helped. Noukan says that because of that there will always be a place for horrible individuals like himself.

After the defeat of Mitsuari Ayu, Noukan is out for a walk in School District 15 with Yuiitsu. They later come upon the Celestaquarium for Noukan's 72nd and final request from Aleister Crowley, the elimination of Shundou Toshizou. Yuiitsu says good luck to Noukan, to which the latter says to wait somewhere away from there as he thinks it is going to be rough. Despite his warnings, Yuiitsu returns near the facility and presumably witnesses the destruction that Noukan caused. Already four in the morning, Noukan meets up with Yuiitsu again, who states that she came back because she couldn't help herself. Yuiitsu suggests in getting a quick meal, to which he declines, much to her disappointment. Noukan then sends communication request to the Windowless Building, prompting Yuiitsu to say that he doesn't have to suck to Aleister Crowley. Noukan states that the Kiharas cannot defeat Aleister Crowley, to which Yuiitsu understands that it is because of his Archetype Controller. Here, Noukan notes that with that power he will able to cut the Kiharas off from their surroundings making science into the archetype of being heretical, making the very definition of their existence non-existent. Yuiitsu remains silent during Noukan's conversation with Aleister.

Magic God Invasion Arc
As the High Priest is bringing the Arrowhead Comet towards an impact on Academy City, Yuiitsu has a brief conversation with Noukan before he leaves to deal with the Magic God, discussing the information they had scattered to manipulate the flow of people during the situation (including some regarding the liquid diamond) and Noukan's idea of romance, making a comment on the use of a giant drill seeming like phallic compensation to an amateur like her, which causes Noukan a little embarrassment.

Quotes

 * (From NT6): "Ahh, ahh. This just isn’t Kihara-like at all..."
 * (From NT7 referring to Yakumi Hisako): "She had been wondering why she got along so well with me. She had my thoughts implanted into her, so of course we got along. She was excellent as a patron who let me do anything I wanted. It was like she was my knight in shining armor. I had all the funding I wanted and all the authority I wanted."
 * (To Noukan, from NT11): "Nooo, you’re a dandy gentleman!! I can’t get enough of that voice!!"