Kei Karuizawa

Kei Karuizawa is one of heroines of the You-Zitsu series as well as a student of Class 2-D of Advanced Nurturing High School. She is a prominent figure in class and is considered to be the girl's leader of Class D.

Appearance
Kei is a teenage girl of average height with waist-length blonde hair that is tied in a ponytail and purple eyes. Her school uniform consists of a light blue dress shirt below the red school blazer with rolled-up sleeves and a short white skirt. She walks in standard school shoes with light blue calf-length socks. She predominantly wears a blue ribbon around her collar. In a more casual situation, she simply wraps her school blazer around her waist and rolls up her dress shirt sleeves.

Personality
Kei is an outgoing person who spends most of her time with the girls at school and Yōsuke Hirata (her boyfriend). Typically she speaks for the girls in the class, acting as one of the leaders along with Yōsuke and eventually Suzune Horikita.

She seems to be a bit of a mooch, as after spending all her points from the first month and D-Class not receiving any, due to their penalties, she asked the girls of her class to lend her some money to buy the 'essentials', managing to gain at least 2000 points from Kikyō Kushida.

She doesn't take notice of less prominent people in the class. This was seen when she mentioned Kiyotaka Ayanokōji being "invisible" after Suzune nominated him as a guard with Yōsuke. Ironically, she befriended him in the light novels and they were very close, even being impressed by his abilities and going on a first name basis as she eventually starts to develop romantic feelings for him.

Background
Kei is a prominent figure of class. Being gifted with an attractive personality, she is considered to be the girl's leader of class D. Her development in the story is worth reading. Despite her looks and attitude she displays and the relationship between her and Hirata, she has her bunch of secrets that she cannot afford to reveal to others.

Plot
In the anime, Kei, like the other first years, listened to the speech given by Manabu Horikita, welcoming the first years to their new school. She was seen in the class talking to Satsuki Shinohara before Yōsuke Hirata asked the class to introduce themselves, agreeing with the idea.

After the teacher Sae Chabashira walked in and introduced to the class the system in which they are supposed to live in now, Kei was surprised at the fact that they received 100,000 private points, to begin with. She was seen talking with Maya Satō and Chiaki Matsushita about clothes and jewelry shopping after the classes that day. At the start of the new month of June, along with the rest of D-Class, Kei was shocked when Class D did not receive the monthly allotment of points, looking depressed throughout the explanation of S-Points and the reason D-Class didn't get any points.

At some point later, Kei went to the pool with the rest of the class, getting especially close to Yōsuke, which possibly indicates that they have been dating since. She tried asking Kikyō to lend her points along with some other girls of the class to buy herself the 'essentials', in which at least Kikyō complied with the demand. She is seen getting closer to Yōsuke, then proceeding to take the mid-test exams and passing with an overall score of 75.

During the anime pool filler episode, Kei saw Suzune walking out of the apartment building, claiming how there were rumors she had died, since no one had seen her over the summer break. Kei then left, dragging Yōsuke with her after Suzune expressed her disinterest in hanging out with the rest of her class when being questioned about it.

Later Kei, like all the other first years, took part in the school cruise, where she was seen calling Yōsuke over to hang out with her friends. When the cruise ship headed to an island, all first-year students were told they need to survive for more than a week with basic materials. Kei got into an argument with Teruhiko Yukimura about the hygienic materials they would need for survival, specifically the need for a toilet. Kanji Ike joined the argument as well, but after setting up camp, he surprised Kei, as he apologized for his words since he went through a similar event when camping as a child. Touched by this, Kei apologized for not understanding his reasons as well.

Towards the end of the survival test week, Kei was found crying in the girl's tent as her underwear was apparently stolen. The girls of her class had Yōsuke check all the boys and their luggage to find it. After minutes of searching, Yōsuke then found the underwear in Kiyotaka Ayanokōji's luggage but refrained from telling anyone, since he (rightfully) suspected that Ayanokōji was set up by someone else.

The next day, Kei and the other girls told the boys to build a separate camp from them because of the incident the day before. Kei had Yōsuke watch over the boys in the class while they moved, but Suzune requested that another boy should check over Yōsuke, since he could potentially be a threat as well. Though Kei defended her boyfriend, she agreed to the request but wondered which boy should help as all the other boys are deemed untrustworthy. Suzune then proposed that Kiyotaka be the second guard since he doesn't seem to have a lecherous side.

Kei recalled that Kiyotaka was often 'invisible' during class, admitting to herself that she barely noticed him being their classmate. In the same night, somebody had started a fire at camp by burning the survival test manual, Kei and the other girls questioned the culprit's identity, first suspecting that one of the boys must have done it. They soon, however, suspected Mio Ibuki because of she was nowhere to be found during the incident. They later learned that Suzune had dropped out of the test because of a fever. They then discussed Mio's motive and whether or not she was the actual culprit and C-Class' leader since her class had dropped out of the test earlier in the week.

The next morning, Kei was seen cleaning in the camp along with the girls. At the time of the class points announcement, she and the entire class were shocked to hear that D-Class came in the first place. Later that same day on the cruise ship, Kei and the others thanked Suzune for her brilliant plan, though, unbeknown to them that Kiyotaka actually planned everything but gave Suzune all the credit to boost her popularity in the class cementing her place as a dependable leader.

{{SpoilerSection|id=lnvol4|

Volume 4
Much to the surprise of everyone, there was another special exam on the ship after their return from the survival island. In this exam, the objective was to find a person deemed as the VIP hidden among the members as the batch was divided into 12 groups based on the Chinese zodiac signs. Kei was placed in the same group as Kiyotaka, Teruhiko Yukimura, Hideo Sotomura, and students from other classes such as Honami Ichinose from Class B, Machida from Class A, and Mio Ibuki and Shiho Manabe from Class C. Kei couldn't hide her dissatisfaction when she saw Kiyotaka and others as her groupmates.

Kei was seen abstaining from the group discussions to expose the VIP, but was often flirting with the handsome Machida from Class A, which eventually pissed off Manabe and her friends. Machida seemed to have taken an interest in Kei due to her cuteness and depicted a protective stance towards her. Manabe and her friends then brought up a previously unresolved matter of Kei having shoved one of her friends, Rika, earlier in the cafeteria and asked her to apologise. Kei feigned ignorance with respect to the accusation and kept using Machida as her shield, which further pissed Manabe off.

After one of their group meetings, Kiyotaka and Teruhiko saw Kei getting cornered in the emergency staircase and being confronted by Manabe and others. Manabe was still accusing Kei for the incident that happened with Rika, but Kei, being stubborn, denied the fact that she had pushed Rika. As the argument heated up, Manabe and others lost their patience and started physically hurting Kei. Even though they began by just shoving her shoulder, this caused Kei to show strange reactions such as breathing raggedly and curling into a fetal position. Manabe and her friends then decided to go a step higher and proceeded to grab Kei's hair, forcefully pulling her up, and saying that they wanted to hit her face. This act of physical bullying led Kei to lose her previous arrogance and attitude, causing her to begin shaking and tearing up to the point where the previous Karuizawa Kei seemed nothing more than a façade. Before the situation could turn worse, Teruhiko, who couldn’t bear to watch it anymore, interrupted them. The situation improved after Kiyotaka said that he had seen a teacher coming, and that it would be best for Manabe to leave. They then left, and Kei recovered from her trauma. She then brushed off Teruhiko, who showed concern towards her, ordering him and Kiyotaka not to let anyone else know about this.

Kiyotaka percieved Kei's reactions as extreme, so he asked Hirata and learned that Kei had been bullied since elementary school. He recognised Kei as a capable person, due to the fact that she had been able to cover up her past using a new persona until now, so he decided to make her his pawn who would obey his orders and work for him in secret. He anonymously testified to Manabe about her issue, then used an invite from Hirata to lure Kei to the ship's lowest level near the engine room and let Manabe's group get revenge for their friend. After Manabe's group left, he approached Kei and told her that he would save her in exchange for obeying all his orders. Kei tried to put up a strong front, but lost all will to resist when Kiyotaka glared deeply into her eye, showing the extent of darkness in his. He informed her that he had secretly taken a video of Manabe bullying Kei, which he would use to protect Kei by blackmailing Manabe's group incase of a situation. Forming a relationship with Kei, he made her go along with his plan, leading to Class A wrongly guessing the group's VIP, to win in his group.

Volume 4.5
Two days before the end of summer vacation, Kiyotaka summoned Kei to a rest area where nobody was present due to the heat. He inquired about her plans for tomorrow and she shared that she was going to sleep all day because she had no more points to spend. Kiyotaka mentioned that she would receive 500.000 points next month and teased her a little about her habit of spending points. After Kiyotaka told Kei the primary reason for calling her out, which was to ask her a favor, Kei expressed her dissatisfaction because he had not apologized earlier for calling her there on such a hot day. He gave her a bottle of tea which she reluctantly accepted. Kiyotaka said that he had been invited to the pool by his friends on the last day of summer vacation. After replying that she wasn't interested in swimming, Kiyotaka asked her if she liked swimming or not, recognising that due to her circumstances, she couldn't swim openly because of the possibility that someone might see her scar. Kei answered that she's probably forgotten how to swim as she hadn't done it for years now.

While Kei intended to question what Kiyotaka wanted because his holiday plan had nothing to do with her, he asked her if the school truly did not know about her past bullying. This made her angry because it was a sensitive topic for her. After Kiyotaka insisted that this was relevant, Kei finally replied that the school didn't know, and even if they investigated the matter, they wouldn't be able to find any evidence. She admitted that she was grateful to the people who had bullied her and to the school that had covered it up, because that's why she was able to grow into a new herself. Believing that Kei wasn't the kind of person who would resort to violence or intimidation, Kiyotaka forbade her to do anything that constitutes as or supports bullying. Kei wondered why she felt surprisingly at ease after telling Kiyotaka about her past, recognising it as odd. She asked if the way he was acting at that moment was his real personality, adding that at first she believed that he was just a gloomy guy but now he was assertive and very direct. He told her to just keep her eye on him to determine what kind of person he was if she was really interested. After that Kiyotaka began to tell Kei about Yamauchi, Ike, and Sudou's plan to peep on the girls tomorrow.

The next day, which was the last day of summer vacation, Kei went to the pool with two of her friends and headed straight towards the locker room, finding the vent Kiyotaka had unfastened and replacing the memory card on the camera. When it was almost closing time, Kei approached Kiyotaka who was then alone, slapping his back from behind before handing him the memory card she had taken from the camera in the locker room. She asked Kiyotaka about his plans and if he was really aiming for Class A. He answered that he was thinking about having someone expelled from the school, which bewildered Kei. She thought that Kiyotaka was definitely not normal, something that she could gauge from looking into his eyes.

While waiting until the locker room was empty, Kiyotaka suggested Kei to swim considering that the area was deserted except for a few lifeguards. Kei refused, but after Kiyotaka said it was an order, she had no choice and reluctantly removed her rash guard while saying that she hated him. Suddenly Kiyotaka grabbed her arm and before she could protest, he shoved her into the pool to which she shouted at him. Following her outburst, Kiyotaka offered his hand to get her up and asked if she had fun. Kei said she didn't, before pulling him into the water without warning and laughed.

Volume 5
At the beginning of September, just a month before the Sports Festival, Class D began making comprehensive preparations for the participation table during the homeroom period when Kiyotaka instructed Kei to object to Horikita's plan, and to then ask Kushida for her opinion. Though Kei agreed with Horikita's plan to pair up the stronger athletes with the weaker ones, she still conducted the order perfectly, and due to her influence in the class, many joined her side. Thus, Hirata concluded that the class should vote to settle that matter. After classes ended, Kiyotaka exchanged looks with Kei but she went out of the classroom with two of her friends. Believing that she might not have understood his intention, he left the classroom, getting surprised when he found that Kei was waiting for him by the main entrance alone. Kiyotaka complimented her for the improvisation but did not answer her when she asked him about his real intention. This angered her because it seemed like he treated her like a dog. Kiyotaka then told her that a traitor would emerge during the Sports Festival, and when the time came, she would understand.

At the beginning of October, during the Sports Festival, Kei had been chosen as one of the horsemen for the first-year girls' Cavalry Battle. When she noticed that Ibuki from Class 1-C led a surprise attack on Horikita, Kei commanded Shinohara to help Horikira's unit, but before they could reach Horikita's unit, Ichinose's unit stopped them. As Kei instructed her unit to go forward, she thought to herself that it wasn't like her to do troublesome things, but for some reason, she did not want Kiyotaka to see her defeated. Kei managed to react well to Ichinose's movements and launched a counterattack, successfully snatching her headband before she fell off.

After first-year males Cavalry Battle, Kei called out to Kiyotaka using his first name without any honorifics, surprising him. Kei expressed her worries for Horikita even though she did not like her as of her mighty attitude, but could still empathize with her due to her experience of being targeted by bullies. During the lunch break, Kei and Hirata joined Kiyotaka for lunch while discussing Ryuuen's strategy as well as the possibility of a traitor. Following the race between Student Council President and Kiyotaka, Kei couldn't hide her shock from witnessing his speed against Manabu. As other students started approaching them, Kei decided to move out of the way for the time being.

Volume 6
In mid-October, two weeks after the Sports Festival ended, Kiyotaka noticed that Kei cast a strange look in his direction before she exited the classroom. As her short, fluttering skirt caught his attention, his name was called by one of his classmates - Satou Maya. Later that night, Kei called Kiyotaka while he hung out in his room and immediately asked if Satou had confessed her feelings to him. Kiyotaka wondered how did Kei knew and she replied that Satou told her in advance that she was going to confess to him. Kiyotaka said that it had nothing to do with her but she argued that she didn't want rumors floating around, and wanted to be sure that Kiyotaka wouldn't tell Satou anything about her incase they started dating. Upon confirming that Kiyotaka and Satou only exchanged contact information and he didn't have feelings for her, they ended their phone call after Kiyotaka reminded Kei to erase records of their conversations from her phone.

A few days later, when Kiyotaka, Horikita, Hirata, Kei, Kushida, and Sudou had gathered for a meeting at Pallet café regarding the upcoming Paper Shuffle Exam. In a different classroom Ryuuen was interrogating Manabe and her friends, asking why they betrayed him. Having no other choice, Manabe told Ryuuen the details of what had happened on the cruise ship, telling him everything including how they were in the same group as Kei and the truth about Kei's past. Manabe explained that she had to spy because she had received threats claiming to expose them unless she followed the instructions.

On October 20, after chatting with his friends and speaking with Horikita, Kiyotaka received a text message from Kei who was reporting on her investigation regarding Shiina Hiyori, confirming that Hiyori was walking around that day asking people if they knew how much sugar Hasabe put in her coffee. Kiyotaka then told her that Horikita was going to contact her the next day, and that they had planned to meet around 8 p.m. Kei wondered why it was so late, to which Kiyotaka answered that he was going to be busy because he was going to watch a movie with his study group. Kiyotaka asked Kei for another favor for which she complained, but later agreed. As they exchanged their goodbyes, Kiyotaka thought that their conversation was over, but he received another message from Kei. It was a cute strawberry shortcake sticker with a bunch of candles on it, along with the additional message of 'Happy Birthday'. Kiyotaka had thought that no one would notice his birthday this year, and was thus surprised when Kei wished him. When he deleted all the texts from their conversation, he felt hesitant to delete the birthday sticker she sent. Following that, he accessed Kei's profile and saw that her birthday was March 8, and he decided to remember it.

At the movie the next day, Kiyotaka ran into Kei and Satou. Kei insisted that this was just a coincidence but Kiyotaka didn't buy it. After watching the movie, the group went to a karaoke bar where everyone from Class D had gathered. Following Kiyotaka's instructions, Kei accused Kushida of acting a little too nice when they were in the middle of studies and pretended to get pissed, proceeding to pour her grape juice over Kushida, staining her blazer. Hirata asked Kei to apologize to Kushida, just as she was about to leave. Later Kei offered to pay for Kushida's blazer to be cleaned.

On the first day of the special exam, as Kiyotaka walked into the hallway on his way to the classroom, where he met up with Satou who had been waiting for him. After they exchanged greetings, Kei appeared and greeted Satou, and pulled Satou to go with her to get a drink before class. Hirata who watched that display mentioned that Kei was a surprisingly jealous person. Kiyotaka didn't understand it, so Hirata explained it further by saying that Kei had been paying more attention to Kiyotaka lately.

Volume 7
It was already Late Deember. After meeting his father, Kiyotaka resolved to put an end to his schemes and movements, which included cutting off his ties with Kei. He called her, asking what she was up to. She didn't believe him at first, but knew that Kiyotaka wouldn't call her without a reason. She began questioning why he was helping Class D from behind the scenes, to which he revealed that he had no choice but to lend Class D a hand, but he then apologized while explaining that the reason his actions had disappeared so he would never contact her again, but assured her that he would still protect her if anything happened as that was a promise. Kei didn't understand why he was saying all of this suddenly, and why he had become so cold. He replied that this was simply the extent of their relationship as of then. Just as the call was about to end, Kei seemed to have something to say but didn't follow up on it.

After the closing ceremony of the second semester, Ryuuen started executing his plan. He had called out Kei out to the rooftop, threatening to expose her past of being bullied if she didn't come. Around 2 PM, Kei showed up on the rooftop; and demanded to know what Ryuuen was after. He replied that he wanted to know the identity of the person he had designated as X, the one controlling class D from behind the scenes; to which she answered she had nothing to say. Despite being threatened that her past would be revealed, Kei argued that if he did that before he could draw the answer out of her, there would no more be an incentive for her to tell him anything and his search for X would be delayed. Realizing that Kei wouldn't budge comw what may, Ryuuen instructed Ibuki to hold Kei down and ordered Ishizaki to fill the buckets with water. When Kei realized what was about to happen to her, she tried to break out of Ibuki's hold but the effort was to useless. Following Ryuuen's orders, Ishizaki dumped water from the bucket onto Kei's head, making her collapse on the spot and start trembling, as she internally relived all the bullying from her past. Ryuuen grabbed her bangs, lifted her up by pulling them, and claimed that she's the sort of person who is conditioned to receive bullying, and that human nature could not be changed so easily. He then dumped the other buckets of water on her, asking again who's the one protecting her by blackmailing Manabe's group. Kei just shook her head and denied revealing even when Ryuen repated this over and over. Ryuuen, who was by then amused, continued this torture, admitting to himself that he's breaking her for his own pleasure.

After they had dumped water on her multiple times, darkness started to rear in her head. She began to blame herself, wondering why she was being bullied, questioning why she was even alive. She wondered what she had done wrong, while Ryuuen laughed in front of her. She was scared, and the bullying she received in the past continuously replayed itself in her head. As she was recalling her past, she wondered if Kiyotaka had abandoned her. Noticing that she trusted X quite a fair bit, Ryuuen then revealed that she was deceived, telling her the truth behind the incident during the shipboard exam, wherein X had deliberately set up her bullying so as to acquire evidence, that she wasn't saved but trapped. Those words caused Kei to fall into extreme despair.

Ryuuen reminded her that there was still one way to save herself, which was to tell him about X's identity, against which he promised that he would never get her involved again. Feeling despair and rage for being betrayed, and her heart wishing to be saved, her lips started moving while still trembling. But to Ryuuen's surprise, Kei shouted that no matter how many times he asked her, she would never tell him, that she had no intention of saying it from the very beginning. Even if starting tomorrow she lost her place at this school, and even if she continued to suffer, she would never give Ryuuen the name.

Ryuuen felt bewildered asked why she still covered for X even though she knew that she was just being used. Kei answered that she didn't understand as well, but she just wanted to act cool until the very end. Despite being baited, she didn't betray him. She was broken but still confident. If she could help Kiyotaka gain the peace he desired, then that would be acceptable for her. Her life had never been as interesting except when she had worked with him, as things had gotten exciting and she had fun. Although she didn't understand most of what she was ordered to do, she felt like the heroine supporting her hero from the shadows. That's why she regretted nothing. Ryuuen declared that she's a person worthy of his respect.

When Kiyotaka showed up on the rooftop, Kei, feeling shocked, asked him why he had come there. He simply replied that he had made a promise, that he would save her should anything happen. Kiyotaka revealed himself as X to Ryuuen, saying that he had come to take Kei back. When Ryuuen threatened to reveal his existence and also Kei's secret, she interrupted him by saying that it was fine, that if everyone was to know about Kiyotaka, then he could reveal her secret as well. She looked at Kiyotaka, and he immediately averted his eyes. Ryuuen grabbed Kei's bangs, tossing her to the side while saying that her role was over. Ryuuen ordered Ishizaki to give Kiyotaka a thorough beating, but as Ishizaki approached Kiyotaka, Kei screamed to stopp him. She tried to get back up and jump onto Ryuuen, but Kiyotaka assured her that she didn't have to worry as he easily caught the fist Ishizaki had swung towards him. As Kei watched Kiyotaka defeat Ryuuen and others, she was left unable to speak a word.

After the fight ended, Kiyotaka approached her and extended his hand, asking why she didn't sell him out to Ryuuen. Kei answered that it was for her own sake while trembling before collapsing into his chest. She admitted that she was scared, but he told her that there was no need to think about anything then, because as of that moment, she had managed to recreate the present by overcoming her past. He confessed that he was the one who hurt her and wouldn't ask to forgive him, but he just wanted Kei to remember that if something like this happened again, he would definitely save her.

Volume 7.5
On December 23, after waking up, Kei noted the change in herself, that she no longer had a horrible past chaining her down. She believed that the events at the rooftop happened because of the seeds that she, who was bullied by Manabe and the others, had planted. It was wrong for her to act tough and continue to take on an arrogant attitude. As she was mulling over her feelings for Kiyotaka, she got a call from Satou asking her to meet as she had something to consult Kei about. After arriving at the Keyaki Mall cafe, Satou offered to buy Kei's breakfast and informed her that she would be going on a date with Kiyotaka. Hearing that, Kei pretended to be calm, and without realizing it, she bit off a larger bite of her scone than usual. Kei tried to recommend other boys to Satou; however, it was all in vain. As Kei was dating Hirata, Satou wanted to know the secret behind making a date a success. Kei mused that there's no way she would know the techniques of romance without having any experience in romance herself. But she didn't want to betray Satou's expectations, so she thought that she should act bold and continue to lie as she was Hirata's "girlfriend." As she was thinking that, she began wondering if Hirata's existence was still essential for her.

To Kei's surprise, Satou told her that she was actually planning on confessing to Kiyotaka on their first date. Kei then asked for Satou's reason for falling in love with Kiyotaka, saying that it might be useful for the date plan was. Satou shyly answered that it was because he was cool and looked mature. Kei sighed as she was trying to overturn her thoughts and act for Satou's sake. They talked about the legendary tree behind the school building, and that if one confessed under that tree, the confession would definitely be successful. Kei wast really bothered after knowing that the date would happen on the 25th; in her thoughts, she labeled Kiyotaka as a boy who just wanted to do lewd things. On the way back from the café, Satou suddenly proposed to have a double date with Kei and Hirata joining as she would be too nervous and wouldn't be able to hold things together if she was alone with Kiyotaka. Kei wondered if someone as steeped in lies as herself could even be of help to Satou, but she agreed after thinking that if she could bring Satou and Kiyotaka together, there would no longer be the off-chance where he would steal her heart away.

When Kei returned to her room, she felt conflicted if she should call Kiyotaka or not regarding his date with Satou. But before she was able to touch the call icon, her phone vibrated, displaying his number on the screen. Kei panicked and answered the call, only be greeted by a flat voice from him, saying that there's something he'd like her to investigate. Having been annoyed by his indifference towards her after what happened on the rooftop, she complained and reminded him of his words he had said a few days ago, that he wouldn't be relying on her anymore. But after hearing Satou's name from his mouth, she listened. He wanted to know who Satou normally hung out with, her pattern of action, her hobbies, and her preferences. Kei said that she would try asking around, and Kiyotaka told her to mail him the details before ending the call. Frustrated that he just hung up like that, she thought that she should've coughed once or twice near his ears.

On December 25, as Kiyotaka and Satou greeted each other before they began their date, Kei showed up with Hirata and approached them. Seeing Kiyotaka and Satou together, Kei asked if they were going out, which made Satou panick as she denied it. Kei continued her teasing, going as far as telling them that they should start dating. After talking for a while, she suggested for a double date to Hirata, saying that she was curious about those two, leaving everyone bewildered except for Satou. Hirata showed his concerns, but Kei insisted that it would be interesting to try something different. As everyone already agreed, Kiyotaka had no choice but to accept the sudden proposal.

Now a part of a double date, the four of them walked towards the movie theater. However, the persistent attacks from Kei didn't end. Rather they continued to increase in intensity. Kei mentioned that Kiyotaka and Satou looked good together and asked Satou not to hide their relationship if they were going out. After saying everything she wanted to say, she left with Hirata, giving privacy to Satou and Kiyotaka. Unfortunately, the conversation between the two appeared to be awkward as they were both silent. As Kiyotaka didn't know what to talk to Satou about and was pondering over the topic, Kei directed a hopeless gaze towards him. Their gazes met for just under a second. Following their silent conversation, Kei finally decided to help him by telling Satou that Kiyotaka just didn't know what to talk about.

Afterwards, the conversation between Satou and Kiyotaka went on smoothly. When Satou complimented him about his race with the student council president, Kei cut in and said that it was hard to believe it all of a sudden, adding that he surprisingly seemed like a cold person, that even if a person precious to him collapsed from a cold, he didn't seem like the type to even visit them. Kiyotaka could feel sarcasm packed in her words and believed that she must be holding a grudge against him. As they came close to the movie theater, a 2nd year from Class A, Miyabi Nagumo called out to them from behind. When Nagumo expressed his interest to chat with Kiyotaka, and the atmosphere became awkward, and Kei approached Nagumo while she was laughing and told him that his face was quite scary. Kiyotaka observed that while the other three from his group naturally just froze up towards this abnormal sight, while Kei was the only one who boldly spoke up to Nagumo, trying to lift the atmosphere.

Later, they went a the family restaurant where they would be having lunch together. As Satou guided them to their seats, Kiyotaka didn't fail to notice towels and splittable chopsticks prepared for four people. When Kei said that they reserved more seats after hearing about this place from Satou earlier, Kiyotaka directed his gaze towards Kei, calling her a liar just by eye contact. Kei answered back by saying that she didn't want to hear that from someone who's never even gone out with anyone before. Just from their gazes alone, they were able to read each other's feelings.

After finishing their meal, Kei declared that they should now go their separate ways. Kiyotaka suspected there was something Kei was aiming for by leaving him alone with Satou. True to his suspicion, after Hirata and Kei had left, Satou confessed her feelings towards him on their way to the dormitory, under the legendary tree. Sadly, Kiyotaka turned her feelings down and said that he hadn't matured enough for romance yet. Satou couldn't hold back her tears and ran back towards the dorm, leaving him behind. After finishing his call with Ikuto Kiriyama, Kiyotaka called out to Kei, who he had figured was hiding behind the bushes, telling her that she would catch a cold if she kept on hiding there. As she approached him, she asked why he turned down Satou-san's confession. He replied that since Satou was a normal girl, she would naturally want a normal romance, and he couldn't give her that. However, Kei denied his statement, and retorted that once you've fallen in love, there would be times when you no longer care about such things, and that Satou would have definitely accepted his true self. But to her surprise, Kiyotaka stated that his main reason he rejected Satou was Kei, that if he had chosen to go out with Satou, Kei wouldn't have been beside him right now. As they were walking, Kiyotaka mentioned that he would meet a 2nd-year student and invited her along.

After 20 minutes had passed from the promised meeting time, Kei started complaining. Kiriyama approached them, directing his gaze towards Kei. He asked for the identity of the girl beside Kiyotaka, to which Kiyotaka simply replied that she was his trustworthy partner. They talked about Nagumo, who had risen to class A and how the exam in the next year would include competition and cooperation between school years. Kiriyama also stated that the only way to defeat Nagumo was to either expel him or to forcibly drag him out of office.

Upon returning from the meeting with Kiriyama, Kei retorted about being claimed as his partner earlier, and lectured him that there was an appropriate attitude and sincerity required if he wanted her to become his official partner. However, since it couldn't be helped, she agreed to become his partner, expecting to get his favor if she followed him. Kiyotaka then told her about the possibility of her getting marked as an target alongside him and how the enemy might use something to expel both of them. She replied that if it came down to that, she would save him. When Kei asked what kind of middle school student he was, he denied her an answer. Kei swore that one day, she would absolutely make him tell her.

As it began snowing again, Kei presented Kiyotaka with a small bag; It was a Christmas present from her, adding that he should be paying her back with a gift twice the amount in return. When asked why she didn't give it to Hirata, she told him that she was unsure of what to do and wondering if she would no longer be useful if she broke up with him. However, Kiyotaka reassured her that wasn't the case; the fact that he never told her to continue her relationship was his answer.

As they continued to chat, he noticed that Kei was back to calling Hirata by his surname but still calling him by his first name. He thought it that was a good opportunity and decided to call her Kei from now on, causing her to panic inside her head. Kiyotaka then revealed that he also had a Christmas present for her. Although she started to complain after seeing it was a pharmacy bag, she still received it happily, and checked the contents. It was cold medicine and a receipt; As she pored over the receipt details, she noticed that it was bought on the 23rd of December. He explained that on his way back to the dorms after buying it, he saw her and Satou together at Keyaki Mall, and even from a distance, he could see that she was healthy, so he concluded that the medicine was unnecessary. Kei was curious about why Kiyotaka didn't attempt to visit her earlier or at least give her a call if he's worried about her to which he replied that because he knew that she hates showing weakness, even if he contacted her via phone, she would try to act tough.

Upon realizing that he had always been worried about her ever since that incident on the rooftop, she felt the sudden need to hide her face, which was rapidly becoming red. She panicked, and inside her heart, there was another her who was squealing while running around. Kei wondered if it was fine to fall in love with someone who has been partly bullying her. But there was no more mistaking it - she couldn't deny her feelings anymore towards Kiyotaka. She had really, seriously, fallen in love with him.

Volume 8
Not too long after the 3rd-semester began, another special exam was being held by the school; it was a training exam in groups that focused mainly on the mental development of the students, to be conducted over seven nights and eight days. Kei received a request from Kiyotaka, asking her to observe and report the situation on the girls' side. On the third day, he decided to get in contact with her. After confirming that Kei was having dinner in the cafeteria with her friends, and that too at the same place for the past 3 days to make herself easy to locate for Kiyotaka, he checked the time and took a seat near her. As he began thinking of a way to make her aware of his presence, she sent him a signal by letting out a squeak. After she succeeded in making her friends going back ahead before her, she called out to Kiyotaka who was sitting behind her. When he mentioned that he didn't have any information on the girls' side of the exam, she felt happy deep inside knowing that she was relied on by him. However, she quickly got rid of that thought, believing that it was weird that she was feeling delighted even though she was being worked to the bone.

Before they started discussing the main topic, Kei asked him why did Ryuuen stopped being the leader of class C, wondering if Kiyotaka's chastisement had worked. He assured her that Ryuuen wouldn't do anything to Kei from now. Hearing him calling her by her first name multiple times, she became flustered. She tried to calm herself down, but after he consecutively called her name three times in the same sentence, she realized that she was being teased. While pouting, she protested that she shouldn't have permitted him to call her by her first name. As they were finally getting down to business, Kiyotaka asked Kei to inform him regarding Arisu Sakayanagi and Masumi Kamuro's group. She explained that both of them were in the same group composed of three classes, with nine from Class A, while not accepting anyone from Class B. Later, he told her that there were a few girls he'd like her to keep an eye on, and named those who were likely to become the key players.

After the conclusion of the Mixed Training Camp, which resulted in Akane Tachibana's expulsion, Kei was waiting on the side of the gymnasium's entrance to meet Kiyotaka. When he came out and started walking through the corridor, Kei marched after him with a slight delay. She expressed her surprise because the situation had turned out to be exactly as he had predicted. He then explained her the reason why Nagumo had used class 3-B for this strategy, and how he had managed to achieve the given results. Before they split up, Kei wanted to know that if she happened to be in a situation similar to Tachibana, say an exam where even a lifeline couldn't be used, what he would do. However, Kiyotaka responded that even without asking him, that she already knew the answer; He wouldn't let her get expelled no matter what method he would have had to use.

Volume 9
On a fine day in early February, just five minutes before the bell rang, Kiyotaka walked into the classroom as he noticed an unusual sight - A circle had formed around Kei, which was causing a commotion. When Horikita asked if he had known beforehand that Hirata and Kei were breaking up, he denied it by saying that it was their private affair. Still, his answer unintendedly caused Horikita to grow even more suspicious. Shinohara asked Kei about the reason for their break up, which she simply answered that she just wanted to think things through on her own since Hirata had spoiled her too much. Nearing the end of the school day, the cataclysm caused by Hirata and Kei breaking up had yet to die down, as Haruka told the rest of the Ayanokouji group that she always thought that they would break up one day, adding that Hirata seemed like he'd appreciate a quiet, beautiful girl more. However, Airi disagreed and mentioned Kei was also cute, before passing it onto Kiyotaka for confirmation, which startled him as he found it difficult to answer.

On the morning of February 14, Kiyotaka sent a message to Kei that he wanted to meet up with her that evening. He suggested a time around five o'clock, to which Kei replied that she had plans to go out with her friends after that. Later that day, they met at a place at a short distance away from the dorms. Kei started complaining about the cold weather and why they had to meet up at that place, but he argued that strange rumours might spread if they were seen together in the lobby, and which would be a problem for her. As he was asking if she was all set for the end-of-year exams, her body stiffened up. He then promised to help her study even though it would have to be in the middle of the night. Afterwards, Kiyotaka showed Kei the unregistered phone number that called him a few days earlier, asking her if she knew anything about it. However, she didn't know and would check it out for him later. After they were finishing their business and Kiyotaka was about to take his leave, Kei called out to him in a hurry and asked what day it was today. But before he got to answer, Kei lightly tapped a small box of chocolate on his head to conceal her embarrassment. She then explained that she was going to give it to Hirata, but there was no longer a reason for her to do that, telling him to thank her by returning the favour a thousand times over.

Shortly after, someone approached them from behind; it was Masayoshi Hashimoto from Class 1-A, who had been following Kiyotaka for a few days, ever since he had left the lobby. When he greeted Kei, she didn't have any clue who he was and turned to Kiyotaka for an explanation. After Kiyotaka introduced Hashimoto, the latter teased them for holding a secret meeting in such a secluded place. He was curious regardind what it was about Kiyotaka that Kei was interested in, since her previous boyfriend Hirata, was one of the most popular guys in the entire school. Kei spoke up that there had been a misunderstanding; she only entrusted the chocolate with Kiyotaka for him to give it to the person she liked. In other words, he was just the middleman. Kei voiced her displeasure against Hashimoto, who continued his questioning. She wondered why he was sticking his neck into something he had nothing to do with. To her bewilderment, Hashimoto drew a few steps closer to her as he reached out his arm and pressed her against the wall behind, asking if she would go out with him. Kiyotaka realised that Hashimoto had been attempting to bait a reaction out of him by making a move on Kei. However, she forcibly pushed Hashimoto away and took her distance away from him before heading back to the dorms.

The next day, February 15, the class fell into chaos once again because of the rumours that had been posted in the morning. There were a total of four of them, and one of them was about Kiyotaka having a crush on Kei. When his classmates asked Kiyotaka for confirmation, he denied it without hesitation. When Kei and the rest of her friends finally got to the classroom, they began to whisper amongst each other while periodically glancing over in Kiyotaka's direction. He thought that it was hard to hear Kei and her friends badmouthed him, so he looked away. After school, the rumours continued to spread with no end in sight. While he was spending some leisure time after getting to his room, he got a call from Kei, and she asking him what was actually going on. He reassured her that she didn't need to worry since rumours always tended to fade away with time. He also added that thanks to the rumour, it should now be easier for the two of them to get in contact with each other. At the end of Volume 9, it was revealed that it was Kiyotaka himself who spread the rumours with Kikyō Kushida's help.

Volume 10
On the second night after The Class Poll was announced, Kiyotaka got a phone call from Kei. She asked him what she should do about the special exam since she wasn't sure about how many people hated her. When he agreed that it wouldn't be strange if she got a few censure votes, Kei snapped back at him by saying that he should be telling her otherwise even if he had to lie. Kiyotaka advised her to act quietly so that she doesn't attract too much attention. Afterwords, they talked about the candidates to nominate for the censure votes in the class, and his plan on picking people he didn't expect to be useful. Before they ended the call, he asked her to inform him if the class already decided on the student to get rid off.

The next day, Kei got a hold of information that everyone was going to vote Kiyotaka out of school, and thus without wasting any time, she called him that evening. She told him that about half of the class would vote against him, and if anyone dared to tell him about it, that person would be the one getting expelled. He thanked her for letting him know despite knowing the risk that she also could end up being targeted herself, which she answered that it wasn't a big deal. Kei wondered what he was going to do; she expressed her worries and said that even though he might seem perfect, he had some flaws.

The day before the exam began, Kei received a text message from Kiyotaka, asking her to spread the rumour about how Hirata intended to sacrifice himself and volunteer to be expelled tomorrow, and for their classmates not to vote against him. Kei then sent the message to everyone in the class other than Hirata and Yamauchi.

Finally, the day of the exam arrived, and just like Kiyotaka had predicted, Hirata went upto the pidium and requested the class to expell him. After the voting ended, Chabashira announced the results, starting with the top three receiving the highest votes. The third and second places were Kushida and Hirata, with the first place being Kiyotaka, which was shocking for everyone. Following Yamauchi's breakdown, Kiyotaka left the classroom with Horikita immediately chasing after him. When she asked how much he knew, Kiyotaka denied her an answer.

Kei, who witnessed that scene, called out to Horikita from behind, wondering what they were talking about. As Horikita said that it seemed Kiyotaka wasn't trusting her, Kei looked at Kiyotaka's back, who was going farther away from her. Horikita implied that Kiyotaka was truster Kei more than her, with Kei asking her the reason for the same. Horikita presumed the reason being her distrust towards Kiyotaka, while Kei trusting him from her botto of his heart. Kei simply replied with a fact, that nobody would trust someone who doesn't trsut them; Those precise and obvious words from Kei caused Horikita to flinch. Horikita then revealed that she was scared to trust him and felt like she would be betrayed, that she would witness something she wouldn't want to. Kei complimented her about her initiative in the class yesterday, but advised that Kiyotaka was a different matter altogether. She told Horikita that if she was scared, her relationship with him could never begin.

Volume 11
On March 8, Chabashira announced the final special exam, Event Selection Exam, to the class. In the exam, each class was paired with another class from the same grade, whom they would directly compete against in seven chosen events. Besides the events, the class must also choose a student as a command tower, the one who would be responsible for selecting students for the events and had the right to intervene in all of the events, effectively making them the leader, but would be explelled if the class lost. Kiyotaka volunteered to be the commander as he was the only one who had a protection point in the class, thus he'd be able to avoid the expulsion even if class D lost.

Later that evening, Kei, who was still in her school uniform, came to visit Kiyotaka's room as per his instructions. When he asked if she just got back from school, she answered that she just finished hanging out with her friends, since she was the star today. Seeing that he had no idea what she was getting at, Kei became a bit irritated and dismissed the topic. Kei was worried that other people might have seen her coming to his room, which could spread some rumors. However, he reassured that since Hashimoto and few other senior students had already seen them together, there was no longer any point or merit in hiding their relationship. She then proceeded to tell him about the relevant information of every girl in the class.

After some banter, Kei asked why they couldn't talk on the phone, but he answered it was easier to talk face to face about those things. She said she would leave soon, seemingly expecting something. In the end, Kiyotaka brought up that he had another matter and took out the present he had bought and gave it to her, saying that it was her birthday present. She was surprised that he knew, given that he acted like he didn't know earlier. He admitted that he was teasing her a bit, which made Kei flustered. He added that it was a combined present for white day and her birthday. She tried to act normal, not looking him in the eye while saying that she'd gotten a ton of good stuff from her friends, so his gift would be better worth her time. But seeing Kei acting like that just increased his teasing attitude more. He deliberately stopped before handing her the present and asked if she was really looking forward to his gift. When Kei denied it, he simply said that he could always take the present back. Not being able to bear his teasing anymore, Kei then grabbed the present out of his hand.

As she opened the cover, she screamed out of surprise seeing a heart-shaped gold necklace. Considering that it was a gift surpassing what friends gave to each other, she had no clue whether to be happy or sad. Kiyotaka realized that it wasn't the best gift at all, so he received a little shock since presents were meant to make the receiver happy. He told her that it cost 20k yen after she asked, he also revealed that he didn't know what to give girls, so he just browsed on the net and used a shopping site selling presents for girls, and since he felt thwt white day and her birthday were almost together, a combined should be a bigger one, so he chose a pricy one. Kei looked at him as if drawing back and said that he might be smart but he was an idiot with these kind of things. She gave him 10 out of 100 on his gift. He asked if she wanted a box of cakes instead, to which she replied that it'd bump him up to 15 points. He said that she could leave it when here before she returned to her room if she didn't like it. She looked at the necklace and him before trying it on and looking at herself in the mirror from several angles, saying it looked a bit childish but her style was great so everything looked good on her anyways. She placed the necklace back in the box and put it her bag saying that since it was his first gift for to a girl, she would take it for him. Kiyotaka thought that was fair, not that he had anyone else to give it to either. Kei wondered if there would ever be a time when she could wear the necklace and go together with him somewhere. She was certain that it would definitely be a very enjoyable day. }}

Abilities
Kei was assessed as being subpar by the school whose absences and grades in middle school were direct reasons for her being placed in D-Class. She doesn't like academics nor sports, but she is surprisingly able to compete with others.

According to both Kiyotaka Ayanokōji and Kakeru Ryūen, Kei has immense mental strength.

Quotes

 * (Monologue) "The arrow of love I had let loose. If it hits, it's a magical arrow that will cause one to fall in love. This one arrow, one way or another I'll make sure to hit Kiyotaka with it."
 * (Monologue) "Jeez ... inside my heart, there was another me who was squealing while running around. There's no more mistaking it. I just have to admit it now. Seriously, seriously, seriously, my heart's seriously been stolen away. The arrow which had pierced my heart. The arrow of love which I could no longer take out. Is this even possible? Is it even fine for me to fall in love with someone who's been partly bullying me? But it's already too late. The power of this arrow is tremendous. I have, I have towards Kiyotaka-really, seriously, I've fallen in love with him.

Etymology

 * The name Kei means "favor, benefit" (恵).
 * Kei's surname Karuizawa means "light" (軽) (karu), "well, mine shaft, pit" (井) (i) and "marsh" (沢) (sawa/zawa).

Trivia

 * As D-Class is for those with defective traits, Kei's defect is her low grades and for previous absences during middle school.
 * Kei ranks #8 in the "Female Character" category in the 2019 edition of 's  guidebook.
 * In the 2020 and 2021 edition, she is ranked #1.


 * For the 2nd Year arc, When asked about her aspirations for the next year, she answered  'To spend as much time as possible with the person I love. And... to become even just a bit more useful to him. That sorta thing?'