Kōhei Katsuragi

Appearance
Kōhei is a well-built young man of above average height. He is bald due to an illness and has a large body frame compared to other students, which contributes to his intimidating appearance.

Personality
Kōhei is an intelligent student who worked very hard to reach Class 1-A that he became one of its representatives.

He is a serious man who adheres to the rules of manners and good conduct, as he reprimanded another student of the class for making fun of Ken Sudō and his classmates. He was calm in telling Ken not to get easily provoked by his classmates' actions, but his demeanor intimidated him into stopping from arguing any further. From this display, it shows he is one of the few upper students who have no problems in associating with those of the lower classes, or that he was simply annoyed by their antics.

He expresses slight anger when some of his failures are mentioned, such as when Kakeru Ryūen brought up his rejection after trying to join the Student Council.

Plot
Kōhei was first seen beside Arisu Sakayanagi, listening to Manabu Horikita as he officially welcomes each first year student into the school.

Kōhei was next seen with Arisu along with several other students being congratulated and was asked the extent of what they know about the S-system.

He is next seen with Arisu looking at the scores of each class, remarking on the advancement of Class 1-C before following with a statement that Kakeru Ryūen is a dangerous man, to which Arisu simply responded by stating everything was "boring" and walks off.

During the school cruise, Kōhei ate lunch at a fancy restaurant within the ship. There, he reprimanded Yahiko Totsuka (Kōhei's classmate) for ticking off Ken Sudō, noting the possible consequence of losing points for bad behavior, and warned him to conduct himself as proper A-Class student should. Kōhei advises the Class D students to keep out of trouble. He then continues on by asking if Ken intends to repeat his earlier blunder, stopping the commotion from escalating.

After arriving at the deserted island, his class set up their camp inside a cave. He was spotted along with Yahiko conversing in front of the entrance by Kiyotaka Ayanokōji. Then sometime later, Kōhei appeared to confront Suzune Horikita and Kiyotaka, fending them off after knowing their intent to go inside their camp.

It was revealed that Kōhei had made a contract with Kakeru, unaware that he was being deceived in the process. Following that, on the last day of the survival test, Kōhei had an expression of disbelief after knowing that his class was ranked third, clueless that it was because of Kiyotaka's elaborate scheme. After that, Kōhei was assailed with voices of discontent by classmates complaining about their losses. Masayoshi Hashimoto came and commented about the outcome being pathetic.

Seemingly unfazed by the insult, Kōhei accuses him of being the one who told Kakeru the name of Class 1-A's leader(Yahiko Totsuka).

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Volume 4
After completing the grueling Island survival special test, yet another special test was announced back on the cruise ship. For this special exam, Katsuragi was placed in the Dragon Group, alongside prominent students from other classes like Ryūji Kanzaki from Class 1-B, Kakeru Ryūen from Class 1-C, and Suzune Horikita, Yōsuke Hirata, and Kikyō Kushida from Class 1-D. On the day when a briefing for each group about to start, Katsuragi was seen talking with Suzune near the door of the room, he praised her for her strategy during the island exam which bringing incredible results for Class D and declared that Class A would attack Class D without mercy next time. As the situation got serious, Kanzaki suddenly appeared, he told Suzune that Katsuragi only trying to get on her nerves and there's no need to waste her time on him. Katsuragi then reminded Suzune that she was just got lucky this time which didn't make them equals. Afterward, Ryuuen came up and walked over to Katsuragi and others, his appearance caused Katsuragi to grow grim as Ryuuen trying to provoke him by referring to Katsuragi as the beast from a little 'Beauty and the Beast' show that Suzune and Katsuragi were displaying. However, Katsuragi stayed calm in the face of that obvious provocation, instead, he struck back against Ryuuen's cavalier attitude with a sound argument before added that he wouldn't let Ryuuen bring his awful attitude to this exam.

During the first meeting of the rabbit group, it was revealed through Machida from Class A that Katsuragi actually had created a "castle gate" strategy for this special exam. Katsuragi proposed that since the VIPs had been distributed fairly amongst the groups, his plan was not to talk at all until the exam was finished so that there wouldn't be a traitor and allow the points to be equally distributed among the classes. In other words, he wanted to play defensively as if he was putting up barriers.

The following day, after the third discussion period ended, Katsuragi got confronted by Ichinose regarding Class A's strategy at the front of Dragon's room. Ichinose asked Katsuragi to reconsider his plan since they need communication to get through the test, adding that she knew Katsuragi had ordered his classmates to refuse to participate in the discussion. However, Katsuragi refused, stating that his strategy was made to protect his class. There were four possible outcomes in this test. As long as they chose one of those outcomes, it was legitimate. He wasn't interested in small group competitions; he was solely focused on maintaining Class A's lead. Ichinose tried to convince him but to no avail. Katsuragi told her that she couldn't change his mind, and she would do the same if she were in Class A. If it was to protect their classes, they didn't particularly mind being criticized by others. After saying that, Katsuragi left.

Volume 4.5
On a certain day during summer break, Katsuragi was caught looking around at the shop by Kiyotaka and the idiot trio, who were there because they went to search for a present for their classmate. Katsuragi glanced around as if worried about something. As Kiyotaka thought that Katsuragi looked like someone thinking about stealing, he unconsciously grabbed his phone, presuming that if he had caught Katsuragi in the act, it could be useful later; however, he immediately rejected that idea. Katsuragi returned the thin box he held to the shelf, took down a similar item, then went through the same motions again, and seemed confused about what to buy. Ike noticed that Katsuragi came there to buy a present for someone and didn't want anyone to see what he was buying. Eventually, Katsuragi had made up his mind and picked a box of chocolates before making his way to the counter, with Kanji Ike and Haruki Yamauchi suspecting he had a girlfriend since the box was adorned with cute wrapping paper and ribbons. They then heard Katsuragi talking to the clerk about the chocolates being a birthday gift for someone on August 29.

At night, the usual group gathered at Kiyotaka's room, with the topic being Katsuragi. Kushida mentioned she didn't know of any girl with the same birth date as above. She also scolded Ike for calling Katsuragi a baldie. Apparently, Katsuragi had lost his hair completely when he was young due to illness. As the group discussed the possible candidate for Katsuragi's present, Kiyotaka wanted them not to interfere more in the matter, but the idiot trio refused before forcing him to investigate it.

The following day, Katsuragi was seen walking from the dormitory building after Kiyotaka had waited for thirty minutes at the crossroads. Katsuragi, while holding a shopping bag, wore the same attire he had on yesterday, which Kiyotaka found odd because the school uniforms did get extremely hot during the summer. Contrary to his prediction, Katsuragi headed towards the school building instead of the upperclassmen's dorms, which explains his uniform attire since entering the school building while wearing casual clothes was forbidden. As Kiyotaka couldn't follow along in his normal clothing, he went back to the shop where Katsuragi had picked out the present yesterday at the Keyaki Mall. He stood before the stacks of chocolate boxes with hearts design and such, trying to picture Katsuragi buying the gift for a man but he couldn't do it.

When Kiyotaka was in the middle of re-shelve the chocolate boxes after his elbow accidentally brushed them, Katsuragi suddenly appeared and asked what Kiyotaka was doing, he was still holding his gift bag. When Kiyotaka stammered that he came here to buy a birthday present, Katsuragi looked down at the scattered boxes, then bent and started picking them up. Ignoring Kiyotaka's words who refused the help, Katsuragi said that Kiyotaka didn't need to worry as the mess might make other customers uncomfortable so they should clean up quickly. They finished cleaning up before they knew it, and Kiyotaka thanked him. Katsuragi asked whether Kiyotaka was buying a present for his girlfriend. Kiyotaka denied it, explaining it was for his classmate's birthday before returning the question to Katsuragi. On being asked about his uniform, Katsuragi answered that he had been going to the school for some private matter. He talked to Kiyotaka about the disadvantages of attending this school, explaining further by stating that he didn't mean being divided into classes, but something that affected all students equally. As Kiyotaka couldn't answer, Katsuragi told him what he meant was the stipulation that you couldn't contact anyone on the outside and asked if Kiyotaka never thought to contact his parents or siblings. After some further exchanges, Katsuragi said that he was the kind of person who tends to agonize over things even if it was just a single present, saying that he couldn't make a snap decision when someone's feelings were involved, that's why he had been visiting the store three times. Thinking that questioning Katsuragi in a roundabout way would get them nowhere, Kiyotaka asked straightly about who the gift was for, to which Katsuragi dodged the question by replying it was personal. With that, Katsuragi headed back toward the dormitory.

Kiyotaka reported back his investigation, stating he still didn't know whom Katsuragi would give his present. Ike and Yamauchi suspected that Katsuragi bought the gift for himself, and started feeling sympathy for him. They then decided to give him a birthday present and celebrate his birthday tomorrow. Although Kiyotaka felt unsure about their conclusion, he chose not to refuse their idea.

The next day, Katsuragi couldn't hide his surprise as Ike and the group suddenly surrounded him. He confirmed that today was his birthday after Kushida asked him, though he was puzzled because he couldn't remember telling anyone his birthday. When Kushida said they wanted to celebrate it with him, instead of welcoming, he put his guard up, thinking that it was a trap laid by Class D. He stated they were not close friends and asking if there were any ulterior motives behind it. Although Ike showed his genuine sympathy that they really just wanted to celebrate his birthday, Katsuragi's mouth tightened before excusing himself as he had his own business at the school to take care of; he was still holding the birthday present bag from yesterday. When Ike pointed out how Katsuragi had been wearing his uniform a lot recently, Katsuragi glared so intently and demanded what he meant. Kiyotaka then helped Ike; he told Katsuragi he was the one who told Ike and others since wearing a uniform during summer vacation was unusual, successfully changed the topic.

When Katsuragi was asked why he was going to school, he still refused to answer and said it was nothing to do with them. However, Kiyotaka insisted something was bothering him because he had been holding the bag since they met at the store yesterday. Katsuragi finally answered he had some business with the student council, but unfortunately, they were out yesterday. After Kiyotaka mentioned that the student council room was being renovated until yesterday, Katsuragi noticed Kiyotaka had some connections to the council and requested Kiyotaka to accompany him, to which Kiyotaka agreed as he also happened to have some business with the council.

At the student council room, Katsuragi voiced his request to deliver a package and message to his family outside of the school, but Manabu Horikita flatly denied it. However, Katsuragi wasn't discouraged easily, as he reasoned that the rules about cutting off contact didn't apply to the package, so if what was sent didn't include any text, information, or communication, that wouldn't break the rules. Manabu clarified that package shipping was prohibited after students were found to hid letters in them without permission. Katsuragi wasn't ready to back down and still insisted he could have the shop deliver it and would go as far as paying his points for it. He also argued since the school was all about fostering one's abilities, they could do anything with enough points. When Manabu asked about the recipient, Katsuragi confessed it was for his twin sister, and he was the only one to celebrate her birthday since they were orphans. However, Manabu still turned down his request as the rules were upheld, further explaining that even though it was possible to use points to buy test scores or barter with other students, those things were never explicitly mentioned in the rules, and the things that were explicitly prohibited couldn't be easily alternated using points. Katsuragi commented if that was true, it meant the rules were full of holes which were odd, but Manabu denied it and said the school purposeful made rules that allow for loopholes. Katsuragi said he understood then glanced over Kiyotaka. Noticing that Kiyotaka was going to stay behind, Katsuragi quietly left the room.

Katsuragi was seen waiting for Kiyotaka in the dormitory lobby as Kiyotaka returned from the council. He apologized for having Kiyotaka accompanying him, then handed the present bag to Kiyotaka, having given up on delivering it to his sister. However, Kiyotaka refused it since the chocolates would be a waste on him. Thinking that Kiyotaka wouldn't be happy with a secondhand gift, Katsuragi bowed slightly before head back to his room. But Kiyotaka stopped Katsuragi in his tracks and said there was a way to deliver the present by disregarding the rules, to which Katsuragi flatly refused because he didn't want to do something that risky. When Kiyotaka insisted that it's worth hearing him out, especially if giving Katsuragi's sister the present was important, Katsuragi then looked around at the people and security cameras, saying that it wasn't something they should be discussing in public.

Upon arriving at Kiyotaka's room, Katsuragi commented the room looked the same as when they first arrived at the school. After they sat down and Kiyotaka poured Katsuragi some tea, Kiyotaka explained that although students were forbidden from leaving the school grounds, there were exceptions for club tournaments, and Katsuragi quickly understood. During club tournaments, the school had to allow certain students to leave the school grounds and travel to outside venues. But Katsuragi thought the school would definitely anticipate that kind of thing, and there would be bag inspections. After Kiyotaka argued there were ways to get past those, Katsuragi was seriously considering the idea. Katsuragi said it would be a huge risk for the student and asked Kiyotaka if he had a talented, trustworthy individual in his mind. Kiyotaka answered he had it, but he needed Katsuragi to trust him if they wanted this to work.

An hour later, Kiyotaka called Sudō to his room to ask for his cooperation since he had a tournament with his basketball club soon. Sudō at first rejected the idea but began to consider it after Katsuragi proposed a reward for payments. Kiyotaka gave Sudō a lunchbox and a water bottle, with the gift box and the bag hidden in them, telling him to mail them through a post when he had the chance. When Sudō retorted that it wasn't an easy task, Katsuragi agreed as well and said the risks were potentially great. But despite knowing the risks, Katsuragi didn't back out which spoke how meaningful his sister was to him. Katsuragi said he couldn't trust anyone in his class to handle something like this and asked Sudō for the favour, adding that he would pay 100,000 points. When Sudō asked why he wanted to go so far as to deliver a package, Katsuragi revealed that his sister was sick. As their parents and grandparents had already passed away, Katsuragi was the only one that could celebrate her birthday. He admitted his blunder because he thought he would be able to send a package after reading the school rules; however, he would still want to give his sister a gift no matter what.

Sudō still wasn't convinced and expressing his worry in case Katsuragi would betray them. To clear their doubt, Katsuragi then answered he would pay Sudō 20,000 points in advance and pay the remaining points as a reward after Sudō completed the task, which would prove that Katsuragi was complicit in the act and they'd both suffer the consequences if either party betrayed the other. Sudō finally agreed as it's hard to turn Katsuragi down since he had told him about his sickly sister. However, this time it was Katsuragi who was having doubts, wondering if they would betray him. To be safe, Katsuragi then explained he wouldn't transfer the points directly to Sudō and they would go to Kiyotaka instead, and after that Kiyotaka would transfer the points to Sudō after he succeeded. It was for insurance in case someone from the school saw Sudō mailing the gift and the deposit wouldn't be traced back to Katsuragi. He also asked Kiyotaka to hand Sudō his phone to record the proof of the present being delivered as Sudō's phone would be confiscated. He was still worried that Sudō was playing with him because he couldn't contact his family on the outside and would have to wait until he graduated to find out if his sister had received the present. When Sudō protested that there was no way he would lie about it, Katsuragi calmly answered that although he wanted to believe him, they hadn't established that kind of relationship yet. Kiyotaka agreed with Katsuragi's idea but said he would use someone else's phone instead.

After leaving Kiyotaka's room, Katsuragi headed back to his room, only to found Ike and Yamauchi standing in front of it, seemingly waiting for him. Katsuragi asked what they were doing, only to be greeted by words of congratulations as they both popped the confetti on him. When Ike said that they came to celebrate his birthday, Katsuragi grew flustered since there wasn't any reason why Class D students wanted to celebrate his birthday. However, ignoring Katsuragi's complaints, Ike forcefully shoved a cake box into Katsuragi's hand before quickly leaving. A confused Katsuragi opened the box to find a chocolate birthday cake that had already cooled down and become muddy, wondering if this was some new form of harassment.

A week later, Katsuragi got a call from Kiyotaka who was stuck inside an elevator at Keyaki Mall. When the elevator arrived on the first floor, Katsuragi, who felt anxious, approached Kiyotaka and asked if he was all right, to which Kiyotaka thanked him and promised to thank Katsuragi properly later. However, Katsuragi answered that there's no need to do that as he and Sudō had helped him a lot. Though there were some lines they couldn't cross because they were from different classes, he thought that cooperation was an excellent thing. Katsuragi then bowed his head in gratitude, telling Kiyotaka if he needed anything else, he could contact him and he would assist him with anything other than the exam.

Volume 5
During the Sports Festival, Katsuragi agreed with Yōsuke Hirata to cooperate between the classes to produce better results in the sports festival. After seeing Kakeru Ryūen refusing Ichinose's offer for cooperation, he warns Suzune Horikita for underestimating Ryūen.

The clear division between the Sakayanagi Faction and the Katsuragi Faction is also shown.

During the tug of war event in the Sports Festival, Katsuragi and Masayoshi Hashimoto briefly argue about the strategy to apply for the event.

Volume 6
During the Paper Shuffle exam, when the school asked each class to choose a class they would want to compete against, it is seen that Class A choose Class B. Kiyotaka Ayanokōji tells this is Arisu Sakayanagi's decision since if it were Katsuragi, he would have preferred an easier class (Class D). This shows that theSakayanagi Faction was gaining the upper hand within Class A.

Later on, Katsuragi comes across Ayanokōji near the water fountain. He then asks Ayanokōji whether the special exam would go well or not, saying that it would be nice if no one gets expelled. After that, Katsuragi starts explaining that he used to be a Student Council Member since elementary school but couldn't become one after entering this school, since he couldn't get Manabu Horikita's attention. Then, when they started to discuss Class A, Kiyo tells Katsuragi that his priority should be to hold his position in Class A. Katsuragi was surprised by Kiyo's statement, saying he didn't expect it a Class D student to be telling him to keep his position.

When both of them got to the dorms, they found a massive crowd in the lobby. It seemed like Kakeru Ryūen had put a message in the mailboxes of all the first years. The letter claimed Honami Ichinose to be collecting points illegally. Katsuragi couldn't understand what Ryūen was planning by signing his name on the piece of paper. Since if his claim was found to be baseless, the school would take disciplinary action against him. He then says that it was a bold step only Ryūen could take.

Volume 8
During the Mixed Training Camp when the students of 1st year had to form groups consisting of 10-15 members, Class A immediately formed a group of 14 and asked one member to come from other classes. Matoba, a member of Class A, announced that whoever joined from another Class would be given special treatment that was, no risk of expulsion. If the group ends at the bottom, the group leader- Katsuragi alone, would be expelled, and he won't drag anyone down with him. It is shown that though Katsuragi was the group leader, Matoba had taken command, showing the change in power within Class A.

Volume 9
On Friday, after school, Katsuragi came across Ayanokōji outside the dorm lobby. There was a huge crowd outside(Similar to Volume 6). Katsuragi was also standing at the same place he was standing before. The only difference was that this time Yahiko was with him. When Kiyotaka asked what the commotion was about, Katsuragi told that a letter had been found outside everyone's mailboxes similar to what happened earlier that year. In the letter was written - "Ichinose Honami is a criminal". Katsuragi told him that if Ichinose were to report this incident, the sender of these rumours would be caught. He then followed by saying that he had a rough idea who it was. After that, he gave a stern look towards a lone girl, who was watching all the reactions of the Class B students. She was a first-year student of Class A, Kamuro Masumi. She was often seen with Sakayanagi, but today she seemed to be alone. When Yahiko asked him whether something was wrong, he didn't answer. Instead, threw the letter into the trash can and got in the elevator with Yahiko. His expression remained stern until the final moment when the gates closed.

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Abilities
Along with Arisu Sakayanagi, Kōhei is one of the leading figures of Class A and even has a faction following him. Due to his failure during the island exam, his faction loses much influence and eventually succumbs to Arisu Sakayanagi's faction. His only remaining supporter, Yahiko Totsuka, is expelled during The Class Poll exam. Kakeru Ryūen views his abilites highly, to the point where he is willing to pay 20 millions points for Kōhei to transfer to his class.

Academic Abilities
Not much is known about his academic background, but it is presumed that Kōhei is one of the top-ranked in his class, as he is one of its representatives. During the Event Selection Exam, he is selected as one of Class 1-A (1st Year)'s representatives during the math portion.

Intellectual Abilities
Kōhei won Honami Ichinose's recognition when she reported him to Chie Hoshinomiya (her teacher), as someone to watch, along with notable figures from each class. This suggests he had enough abilities to pose a threat to Class 1-B.

Name Etymology

 * The name Kōhei consists of kanjis that mean "peace" (康) (kō) and "level, even, peaceful" (平) (hei).
 * Kōhei's surname Katsuragi consists of kanjis that mean "arrowroot; kudzu" (葛) (katsu) and "castle" (城) (ragi).

Trivia

 * Kōhei shared the same student identification number with Haruki Yamauchi.
 * For the 2nd year, his ID is changed to the same one as Sō Shibata's.

 
 *  For the 2nd Year arc, when asked about his aspirations for the next year, he answered  'To temper myself. I'm ashamed of my immaturity, so I want to become stronger. Not only physically, but also in spirit.'