Mio Ibuki

Appearance
Mio is a teenage girl of average height with short blue hair that has single small hair strand sticking up and purple eyes.

She is usually seen wearing the school uniform with a blue bowtie and orange shirt. Like all the other first years, she wore the red tracksuit over the special island exam period.

Personality
Mio rather prefers acting alone to socializing, which is one of the reasons why she is often isolated in her class.

Unlike her peers, she doesn't seem to enjoy the violence inflicted on others as shown when she flinched after Kakeru Ryūen smashed a glass bottle on the head of Daichi Ishizaki or when Albert Yamada was ordered to beat Daichi and the others for their failure in attempting to get Ken Sudō expelled. She made it clear that she disapproved of their cruelty and wanted them to stop their actions.

She doesn't like being insulted as demonstrated when she told off Kakeru for treating her like a plaything when he made advances on her. She appears to not like being pitied as shown when she angrily slapped away the hand of Kiyotaka Ayanokōji despite him trying to help her up after she was knocked to the ground.

Due to her time with Kakeru, she has come to expect mistrust or deception and even accusations towards herself. She told off Kiyotaka and his group to leave her alone when they enquired about her. However, she is capable of being surprised, like when people actually give her the benefit of the doubt, shown as she was caught off-guard when Kiyotaka stated he trusted her after some panties were stolen from the girl's tent during the island exam. She was so shocked at his belief in her that she nervously blushed while thanking him for it. She was also seen curious, when Kikyō Kushida and Haruki Yamauchi commented on how incredibly close Suzune Horikita and Kiyotaka were lately.

She is very deceptive as it turned out she infiltrated D-Class to steal the key card from Suzune while she was cleaning herself off, despite the class showing her kindness by taking her in and providing food and other necessities. She showed no remorse in stealing the card, even defeating Suzune in a fight.

Plot
Mio Ibuki made her debut sitting at the karaoke bar of Keyaki Mall where she is seen flinching after Kakeru Ryūen's smashes a glass bottle over Daichi Ishizaki's head.

She is later seen with Kakeru and his henchmen after failing to get Ken Sudō of class D expelled. She looks away as Albert Yamada proceeded to beat up Daichi again for failing in his attempt to expel Ken.

During the school cruise, Mio confronted Kakeru where she demanded him to stop his actions, but he disregarded her words and told her to come back to his room while putting his arm around her. Disgusted by him, she slapped away his hand and demanded him to take her words seriously, but she was ignored as he walked away. When she tried to stop him, Albert intervened, in which she called him a puppet for following his every order and tried once more to speak to Kakeru but Albert got in the way and pushed her against the rails telling her to stop. Kiyotaka Ayanokōji came to help her up before she angrily slapped his hand away and chastised him not to get involved in her business and stormed off.

During the survival test, Kiyotaka, Airi Sakura and Haruki Yamauchi found Mio injured where she had bruises on her face and was slumped against a tree. Mio was then taken back to class D's camp by the group despite protesting that they were enemies during this test.

The morning after the underwear theft incident, Mio approached Kiyotaka as he was working on pitching up the guys tent. She stated that she finds the theft unforgivable and tells him that she is aware that people like Ken would believe she was the one behind it because she was an outsider. Mio stated she knew Kiyotaka holds the same belief but he reveals that he trusts her, his reply catches her by surprise. She thanked him and blushed nervously. Since then, she was seen becoming more curious about Kiyotaka's relationships with other people, turning around and stealing glances when Kikyō Kushida and Haruki Yamauchi both commented on how incredibly close Suzune Horikita and Kiyotaka were lately. While doing so, she caught a glimpse of the leader card in Suzune's possession. Since her camera had been mysteriously destroyed, she managed to steal it while Suzune was taking a bath by herself in the waterfall, after Haruki poured mud on her.

Shortly afterwards, somebody started a fire at camp, burning the survival test manual leading to even more trust problems within D Class. Mio used this as an opportunity to sneak away from the camp.

Suspecting that the incident was Mio's doing, Suzune searched for her and found out that she stole the leader's key card. Mio attacked Suzune, despite the rules prohibiting violence against students from other classes knowing that as long as nobody noticed, she could get away with it. Taking advantage of Suzune's fever, Mio defeated her and brought the leader card to a student who requested evidence.

It was later revealed that Kiyotaka had deduced that Mio was a spy sent from class 1-C. Kiyotaka was also the one who found Mio's hidden camera and two-way radio in which he saw Kakeru possessing the same one as hers the other day at the beach, deducing that he had not left the island and was lying hidden somewhere until the test was over. Kakeru had it all planned out to deceive everyone to gain the most points for his class in the test. Kiyotaka then began to stage certain events so that Mio could find out who the D-Class' leader was, so she could fulfill her mission and leave them. Kiyotaka had planned to change leaders for class 1-D after classes 1-A and 1-C have verified for themselves that it was definitely Suzune's name on the card. Kiyotaka then executed his final plan, after Suzune's health deteriorated to the point that it became a valid enough reason to change leaders for their class. After the island test was complete and C-Class came last, Mio apologized to Kakeru about incorrectly guessing class 1-D's leader (although she was right but Kiyotaka had changed leaders without her knowledge), in which he forgave her as he recognized that someone has outwitted them, leading to their loss and class 1-D's victory.

{{SpoilerSection|id=Mio|

Volume 4.5
In late-August during summer vacation, Mio went to a fortune-teller in Keyaki Mall, which had become a hot topic among the students. However, upon arrival, she found out that she couldn't have her fortune read if she was alone. As she angrily complained, she caught Kiyotaka's eyes who was walking away from the line next to her. When he pretended that he hadn't seen Mio, she chased after him and inquired him about Suzune, to which Kiyotaka simply replied he was alone for that day. However, Mio still hadn't given up and asked if he was going to invite Suzune since fortune-telling was usually something they did one-one and how she didn't expect this, but he told Ibuki to just reach out to Suzune herself and telling her that she wanted to have their fortunes read together. Mio refused because it's not like she had anything to talk to Suzune about. When Kiyotaka asked if Mio was upset about not having her fortune read, Mio shook her head in frustration and said that it would be lying if she said that she wasn't annoyed, but she didn't have any choice unless to give up. Kiyotaka suggested inviting Ryūen, which earned him a scornful glare packed with disgust from her. She mentioned that she hated seeing Ryūen's face and would rather avoid him during her holiday. When Kiyotaka pointed out about their closeness back on the cruise ship, Mio looked away and mentioned she only did because it was her fault that she didn't discover Class D's leader.

Their conversation shifted about the island exam's result, with Mio asking Kiyotaka about D-Class's leader to which he gave a vague answer. Kiyotaka tried to change the topic, wondering why Mio couldn't simply invite a classmate to come along. Mio answered that she despised the girls in her class and how the mood always turned sour no matter what she did. Even though Kiyotaka refuted that she was making conversation with him just fine right now, Mio insisted it wasn't true and calling herself prickly. She told him that talking to people made her anxious, and when she was anxious, it put her on edge and it's not like she wanted to be that way. Finally realized that she had talked too much, Mio became flustered and turned away, not wanting people to get the wrong impression about them. 'After chatting for a while, Mio decided to leave the place as it is seemingly impossible to get in individually, though she couldn't hide her disappointment and muttered how she was interested in tenchuusatsu. When Kiyotaka asked what it was, she sighed in exasperation, not expecting him to come to fortune-teller without even knowing what it was. She then explained it was a type of fortune-telling that told people what times were unlucky for them; that's why she came here because fortune-telling wasn't all about romance and such. Looking back at the long line, Mio said although it wasn't about romance, people here seemed to after that stuff since they forced people to visit in pairs. After saying that, she left.

Mio coincidentally met Kiyotaka again on the next day at the same place. Mio was disgusted and asked why he came there again. When he asked her the same, she simply replied that she came here hoping the rules had changed since yesterday. After Mio lectured him about how people who were overly sceptical in fortune-telling wouldn't get anything out of it, he proposed them to go together as a pair since they were both genuinely interested in fortune-telling. Mio was worried that some Class D students still held a bit of grudge toward him because of what happened on the island, and if his classmates saw them together, they might resent him. However, Kiyotaka reassured her that she didn't need to worry because people who operate based on feeling wouldn't be admitted to this school in the first place, adding that spying and sabotage were natural tactics to employ under the circumstances.

Mio and Kiyotaka both got in line. Because they were only together to have their fortunes read, she suggested not to make pointless chit-chat while waiting, to which Kiyotaka agreed. After spending a long time waiting, they got in and proceeded to get their fortunes told. As they both received rather generic results, Mio was said to have a long lifeline on her palm. The fortune-teller was carefully providing her with predictions about academics, financial success, love, and so on. Even though they were ordinary and innocuous, she listened with satisfaction. During Kiyotaka's turn, Mio exclaimed in surprise when the fortune-teller said that he held the fate of tenchuusatsu, which meant that he had lived a life of constant misfortune since he was born. However, the fortune taller refuted Mio's statement, saying that the little girl wasn't quite right when she said that he tenchuusatsu meant he lived a life of misfortune because people alone decided what they could do and couldn't do. After the session was done, they were told to go back straight after leaving, without taking any detours in case they might be stuck for quite a long time.

While heading back, Mio expressed her satisfaction towards the fortune-teller, telling Kiyotaka that the fortune-teller was actually pretty famous and highly accurate. As they headed towards the elevator, they found students crowded the area, so they decided to take a detour to a different elevator. Remembering about a warn earlier not to take any detours, Mio met his eyes for an instant and wondered if it was a coincidence or an inevitability. In the end, they decided to take the detour to find out how accurate the prediction was. When they arrived at the elevator, no one else was around. After Mio agreed, Kiyotaka pushed the button for the first floor and the car began to move. However, as the third-floor light blinked on, the elevator made a heavy grinding noise then stopped. The lights went out for a moment before the emergency lights came on.

Kiyotaka tried the emergency button but there was no response. He then suggested Mio call the school from her phone. Even though at first Mio refused, she still pulled out her phone while grumbling. Unfortunately for them, her phone's battery was low and immediately afterward, it died. Since she didn't have anyone to talk to, she didn't usually notice when her battery was about to die. Having no other choices, Kiyotaka took out his phone but the battery was at only four percent. Mio called him useless and asked if he would call someone he knew to rescue them. When Kiyotaka mentioned Suzune, Mio rejected the idea as she didn't want to show her weakness in front of her rival. Kiyotaka manages to call Kōhei Katsuragi for help, so the only thing left to do was sit and wait. Not long after, the air-conditioner stopped working and Mio began to feel upset. She asked if there were any possibility they could escape on their own, to which Kiyotaka replied that there was an emergency hatch. Mio wondered how they were supposed to get it open since the hatch was probably kept locked from the outside, but he reassured her that it was wiser to wait.

The temperature continued to rise as they waited quietly for about thirty minutes; however, they still hadn't heard from anyone. Mio couldn't take it anymore and kicked the elevator wall with all of her might, leaving a dent. She kicked again; the elevator wobbled slightly but showed no sign of actually moving. Kiyotaka suggested to try open the hatch on top. Wasting no time, Mio leaped upwards directly beneath the hatch and tried to push it but to no avail. Mio, who was growing impatient, said she would kick it, to which Kiyotaka commented it was impossible. But Mio insisted that the amount of force needed to open the hatch should be minimal since the rescuers need to be able to open it from the outside. She looked at the elevator walls, planning to kick off the wall and launch herself but Kiyotaka stopped her and tried to change the subject. He told her that there was another way, saying that elevators usually had something like a cancel command function, so there should be some commands in express mode, and it would take them directly to the first floor. Mio started pushing various buttons, but after many failed attempts, she whined again and punched the wall to relieve some frustration. She asked Kiyotaka if they had already tested all button combinations. He answered that there was one last command, even though he didn't expect it to work. He told her to push the button for the first floor plus the close-door button at the same time. But to their surprise, the elevator started to move.

Two adults checked on them when the elevator arrived. Kiyotaka and Mio found out that both of them apparently hadn't caused the elevator to move using express mode or anything; they just happened to push the buttons at the exact same time the adults operated the elevator remotely. When one of the adults said that they must have a rough time there, Mio agreed and commented that fortune-telling was serious business.

Later, Mio assisted in helping Kakeru find the mastermind in class 1-D, dubbed "X" by the group, and while Kakeru attempted to narrow down the suspect, Kiyotaka comes forth and admitted himself that he is indeed Class D's mastermind. Mio, in denial, disagreed with the statement, still thinking him to be just a stupidly nice guy and tried thinking who else might be X. However, when Kiyotaka revealed his knowledge of her plans in the survival test and that he was really the one who sabotaged them, this surprises and confuses her. After Kei Karuizawa was eventually cornered and abused by Kakeru to get at Kiyotaka, which got his attention as he came to help her out.

Mio watched stunned as Kiyotaka swiftly took down both Albert and Daichi, with her realizing it was all true as she entered a state of disbelief at his abilities. Afterwards, Mio took her turn at fighting him, he easily dodged all her attacks and her questioning about whether he was X, in which Kiyotaka bluntly answered "After all this, you still don't believe that? (referring to him being X)". Mio simply replied that she was just too confused or upset about Kiyotaka being X before getting knocked out cold by a kick from him.

The next day after Kakeru's defeat, Mio met with him in the school lobby, in which she said that if Kakeru wanted to leave the school that he would have to fight her first. Ultimately, he didn't go through with it but Kakeru stopped associating with her and his gang.

In the special exam in the Second Year arc, she teamed up with Suzune Horikita despite her earlier reluctance of working with her }}

Physical Abilities
Mio is shown to be a capable fighter, but she is not as strong as Kakeru Ryūen who dodges her attacks and overpowers her easily. In the special island exam arc, she defeated Suzune Horikita in combat, however, it was not clear who would have been stronger if Suzune had not been running a fever. It seems though Mio has taken Capoeira, a Brazilian martial art, as her main fighting style. Despite her skill, she is an inferior opponent against Kiyotaka Ayanokōji who easily swat her aside and Ichika Amasawa who did the same although both opponents were heavily suppressed. She is considered to be the strongest girl in second year which Horikita agreed to that notion.

Name Etymology

 * The name Mio consists of kanji that mean "water route, shipping channel" (澪).
 * Mio's surname Ibuki consists of kanjis that mean "that one" (伊) (i) and "blowing" (吹) (fuki/buki).

Trivia

 * Mio shares the same student identification number with Masumi Kamuro.
 * For the 2nd Year arc, When asked about her aspirations for the next year, she answered  'I don’t have any ambitions or whatever... Ah, no well, maybe just this one thing.'