Knowledgeable in both science and magic, he plays a key role in the workings of GREMLIN, who uses science and magic hand in hand. Behind the coat and a helmet lies a cold and distant former Kihara who strikes in Baggage City to carry out his revenge on the person responsible for an incident that ruined his life.
As a notable trend among the Kihara family having given names related to science and mathematics, his given name (加群) can be translated as Module. Meanwhile, his Bersi alias is derived from the little known (to the English-speaking world) Kormak's Saga of Iceland, which is related to his magic.
During the events in Baggage City, he is seen wearing a white coat that covers of his body with a belt tightened around his waist (with the belt buckle bearing a serpent or a dragon), black shoes and gloves, and most notably a white helmet that obscures his identity.
He is a rather tall man, with a lean build, almost adrogynous. When his helmet got destroyed, he is seen to have black eyes, and short black hair, which was somewhat spiky, though not to the extent like that of Kamijou Touma or Tatemiya Saiji.
He is a Kihara, as such he has a natural affinity to science and the gravitation towards evil. However, he somehow managed to overcome both of this, becoming a magician, as well as helping the audience of Natural Selector, and other characters. Yet, he is still a Kihara regardless, as he displays his deviousness, having manipulated events in Baggage City as so he can face Kihara Byouri equally, as well as allowing for the events of Radiosonde Castle, and the invasion of Hawaii to take place. Therefore, he is considered to be like the other Kiharas. He is someone who will let nothing get in the way of him achieving his goals, even if he is good.
As a Kihara, he commited experiments related to stopping and starting the heart safely and was considered a genius for it. However, he eventually seemed to develop a conscience through his actions and became a teacher, thus abandoning his role as a researcher and betraying the ideals of a Kihara. After he killed a murderer who was a threat to his students, he realised that the scenario was set up by Kihara Byouri and, despite being acquitted for the crime, he quit his job. Later on, he begins working to bring Byouri down to avenge the person she turned into a killer and he himself killed, convinced that justice was not done until either of them were dead.
He also appears to be aware of Kamijou Touma's existence and has confidence in the fact that people who end up involved with him usually come out of things unharmed no matter how bad the situation gets, which led him to advise the seemingly doomed survivors of Baggage City to seek him out.
Originally, he was a near-death experience researcher who eventually gained the ability to safely stop a person's heart and restart the safely stopped heart, having become evil as part of the Kiharas on his teens. He was also able to control the number of times he could stop a person's heart, which made him legendary amongst the Kiharas. As a researcher, he killed the most number of people out of all Kiharas, but as he revived those he "killed", no one was damaged by his actions. He ended his research before he was twenty after realizing that since he could kill and revive people easily, regardless of the reason that the value of human life remains the same, it would always be judged at a very low baseline. Basically, he felt that with his skill over life, it could be compared to that of a child turning a television on and off.
He later became a teacher, which was easy as he had erased his past as a Kihara. As a teacher, he took part in Student Keeper activity, which was one of the safety measures of Academy City to prevent students being unable to return to the school life due to them skipping class. During the activity, he managed to reach what lied deep inside a student's heart and effectively convince 32 students to come back to school, which earned him some fame. He also warned them of the Kiharas, "the dangerous darkness in Academy City". During this time, he also built up a network of adults who could pick up on SOS signals in casual conversations between children at places where they gather to use their allowance, which Kihara Noukan would later continue to observe.
He resigned from his job about 3 years prior to the series' events due to an incident arranged by a fellow Kihara (Byouri) that corrupted a young man erased him from the records to attack a group of Kagun's students (which included Kumokawa Maria). He charged towards the attacker, damaged his consciousness and killed him before a tragedy could occur. Despite the court's verdict making him innocent and his teacher licence still active, he decided to take revenge on whoever arranged the incident and disappeared from Academy City.
By that time, he met Marian Slingeneyer and helped her to improve the Dvergr tools that were essential for their survival, while he began to study magic. He also developed spells for the sake of "carrying out the perfect tie against his one mortal enemy", which were deemed too dangerous to touch by GREMLIN magicians. Marian intentionally drawn Kagun into GREMLIN and he became one of the organization's science oriented cores that provided assistance when members had to rely on scientific technology to carry out their plans. At this time, Marian bonded with Kagun, and clearly cared for him as a colleague, and is described as being her partner, telling him to return to her if he has finished his vengeance, unaware of the meaning of his version of revenge.
Preparing for the possibility that his mind and body might get controlled if he fails in defeating Kihara Byouri, Kagun implanted a semiconductor in the back of his neck, within it are things that Kagun would do given certain conditions. However, a tiny effect would appear only when he was forced to do something that was "not like him". To ensure that he would take actions that were "like him," a list of rules on the device were inputted: 1. He would exterminates his enemy, Kihara Byouri; 2. As long as it did not interfere with 1, he would limit the loss of life of both enemy and ally as much as possible; 3. To achieve 2, the damage or destruction of anything other than human life was allowable.
Shinyaku Toaru Majutsu no IndexEdit
Baggage City ArcEdit
- Main article: Baggage City Arc
He intercepted the scope of the invasion force Academy City would be sending (and from here, knew of Kihara Byouri's participation), and later made the final adjustments for the experiment to give GREMLIN a better advantage. He and Othinus alone, knew of the the true extent of the experiment and what the GREMLIN was getting into. He first appears in the early parts of the distortion that occurs in Baggage City with Academy City and Science Guardians forces. Here, unwittingly saves Shar Berylan from an attack of a Five OVER Modelcase "RAILGUN", defeating it by only using his fists.
Kagun reappears at the heat in the battle between Oumi Shuri and Kihara Enshuu. He aids Shuri against Kihara Enshuu, where the latter realizes that he may be Kihara Kagun. During the fight, Enshuu charges towards Kagun, to which he responds by using a convex landmine, and reminds Enshuu on how the action he was doing is what it means to be a Kihara, detonating the mine in close range, but due to its shape, it protected Shuri and Kumokawa Maria who was with her, unconscious. However, Enshuu got away, and Kagun was forced to use his magic as protection against the blast, regardless the battle was over. Shuri hesitating in trusting Kagun, draws out her kunai spade, but Kagun tells her that she will not to be able to defeat him with too much strength. Kagun states that he is a specialist of Kiharas, and he doesn't want to fight. Finally, he advises her to meet Kamijou Touma if she wants to survive. He later tells that he has his own objective and that he will not be able to protect them, as he is a Kihara himself. Unaware to him, Kumokawa Maria was searching for him the entire ordeal.
During her conversation with Sigyn, Marian references calling "Bersi" as she was tired of all the work he has to do. Bersi himself appears before Marian Slingeneyer after her retreat from her fight with both Kumokawa Maria and Oumi Shuri, who is elated at his appearance.
Finally, after the defeat of Kihara Enshuu at the hands of the combined efforts of Kumokawa Maria, Saflee Opendays, and Oumi Shuri, he finally meets up with Kihara Byouri. He stops her attempts at killing the three, and as a price, has his helmet destroyed, revealing his identity to her. Here, he reveals that he manipulated events, in order for Byouri to lose all of her safety devices, so that he can fight her on the same level, and as proof that he had killed her. Kagun blames Byouri for corrupting the attacker of his students that forced him to kill him in front of them. The attacker was a pawn prepared by Byouri many years ago, in order to force Kagun in giving up becoming a teacher that is looked up to, someone who is so unlike a Kihara, and now redemption for him is to kill her.
She attacks him with her projectiles, as her Skyfish form, but Kagun goes unscathed after getting hit by her. Here, he reveals his power, a laser blade that he held between two of his fingers, demonstrating his power by severing her right arm. However, Byouri then reveals another of her transformations, Yeti, allowing her to form a gigantic furry arm and tries to crush Kagun, however, he lives and remains unscathed. This confuses Byouri, not knowing how Kagun is able to achieve such a queer power that is beyond her knowledge in science. With her Skyfish form, Byouri attacks Kagun, hitting him but remains uninjured. Kagun attacks Byouri still, and pulls her down to the level where he was tried to be crushed by Byouri using his Yeti transformation. While she was preoccupied with figuring out Kagun's powers' relation to science, Kagun manages to "shift" her head, something that should be certain death, however, she once again reveals another form, Little Gray. This transforms her limbs to exapand into a large blob. Using this, an explosion occurs and engulfs Kagun, though he remains uninjured his clothes are torn, while Byouri is damaged yet is quickly recovering, at the cost of her becoming deformed due to her transformations.
Byouri then conjectures that since Kagun is using powers beyond her ken of science, she believes that may be a part of GREMLIN. Determining his weakness, Byouri attacks a non-fatal blow upon Kagun, and hither she realizes she is correct. Kagun confirms this by stating that his power, Whitting creates miracles that allow him to survive if he is faced with a great disadvantage, making him avoid damages. Kagun continues that the Number 2 Level 5, may be taking over her, as the reason why she only used her power until only the very end. Suddenly, Byouri transform again into Loch Ness, forming into a giant monster. Seeing this, Kagun reveals that he is not planning to win, and would rather have a stalemate were the both of them die. An explosion occurs, and the both of them fall into Maria's path, and here, a severely injured Kagun stabs Byour's monster head, and wrenches it off clean from its body. 
Maria seeing her teacher again, runs towards him, though he is unable to focus on her as he collapses on the ground. Kagun looks up to Maria, and simply said sorry to her as he dies. Maria could only shout and cry and try to remind her dead teacher that he has saved them and are grateful to him, and what he has done wasn't futile. More importantly, Marian witnesses the death of Bersi, her partner, as well breaking down completely, despite the warnings of Othinus, she begins to start using Dáinsleif.
Near the end of the arc, after the great many events that had passed after Marian used Dáinsleif, and was later defeated by Kamijou Touma. Othinus later revives Kagun as an Einherjar, and have him carry Marian, where after she comes to, recognizes him by the nostalgic feel of his skin and scent. Despite Othinus making Kagun's actions in vain, Marian does not protest, as she is too tired. They later discuss their future plans while walking in the snow, while the walking dead Kagun carried Marian.
Ichihanaran Festival ArcEdit
- Main article: Ichihanaran Festival Arc
Othinus continues to use Kagun as a Einherjar, and is referenced by Thor as the only thing that keeps Marian from becoming desperate as she can still smell his scent from him. It is the reason for Marian's listlessness.
Other than Marian, his legacy continues to haunt Touma, for not only not being able to save him, but also the fact that he was being manipulated by Kagun into his plans back in Baggage City, making him more wary of people wanting to use him.
Later, as Thor and Touma prepare to break through the Windowless Building, he mentions that due to Kagun wanting revenge against Byouri, he planned out ways to combat her in places other than just Baggage City. As it was possible he would end up confronting her in Academy City, he set up a few tricks before leaving the city. These were free pass IDs in the supercomputers of a few research facilities, which are normally inaccessible to the likes of Thor and Touma. 
Magic God Othinus ArcEdit
- Main article: Magic God Othinus Arc
GREMLIN invasion of TokyoEdit
- Main article: GREMLIN invasion of Tokyo
Othinus and the other core members of GREMLIN are in their base at Sargasso making the preparation to forge Gungnir. Othinus then asks each of the members regarding the status of their assigned tasks and asks how's Bersi (Kagun) doing to which Marian replies that he should be performing the final tests for the parallel processor now.
Kagun is later shown to be silently working on the parallel processor that will be used to send signals to produce Dark Matter. His job is to find the computers from the radios, fish finders, navigation control systems, and other devices installed on the dozens or even hundreds of ruined ships that had drifted to Sargasso. Once he finds them, he will then connect them with cables and make some programming adjustments so they can function as a parallel processor. This high-speed and large-scale processor is necessary for them to be able to use the empty husk of the #2, which had been retrieved from Academy City.
Once the parallel processor was finished by Kagun, he sets it up to send signals to Kakine Teitoku's flesh and blood organs in order for it to produce Dark Matter. After some time, the organs produce a white sticky substance and the gathers to form Kakine's own body. Othinus and Kagun both realize that Kakine is already conscious. After hearing the conversation of Othinus and Kagun regarding using him for their own purpose, he starts to devour all the equipment attached to him and declares that all he knows is their fate for using him as a tool then attempts to attack them. He forms a dome around the headquarters of GREMLIN and proceeds to attack. Before the attack arrives, Othinus subdues Kakine by unhesitatingly grabbing his neck in one hand, digging her fingertips to his neck. At that instant the dome collapses. Othinus and Kagun then exchanges a few short words. Othinus then forces Kakine to submission and transforms him into a mass the size of a volleyball then tosses it to Bersi and commands him to do what needs to be done with it. She then senses that their base was already found by their enemies. Once Kagun's assigned task is completed, he is then instructed by Othinus to intercept their enemies and destroy what needed to be destroyed to buy them time while producing the lance.
Later, just when Touma and the others were about to be attacked by Nidhogg, Kagun comes and attacks it. He successfully defeats Nidhogg and Kumokawa Maria recognizes him. Maria finds that there is a slight scar on the back of his neck. It turns out that there is an embedded chip there that is programmed based on a list that he has inputted in the device. That list comprises of the things that he would "actually do" or actions that are "like him" so as to ensure that even if he is dead he won't be controlled to do what he does not want to do. Maria then realizes this and tells Touma and the others that she would stay with him until the end.
Shifting and Fluctuating WorldEdit
In the final recreation of the world by Othinus created specifically to break Touma's spirit, known as the Version_Omega world in-text, where several characters from the original world have been "saved" or have not experienced great tragedy, Kihara Kagun, who is apparently still a member of GREMLIN, is first seen by Touma in the park where Othinus put Touma in after recreating the world. Alive and well, he is found by Maria who is apparently looking for him.
Later, as the now-broken Touma partakes his "last meal" as he decides on the method on how he should kill himself, he sees Kagun and Maria again. She asks what they're going to do now, to which he states that there is a festival nearby and they should check it out. Maria becomes excited and laughs, believing it to be a festival date with yukatas, and that her ability is going to let out a roar. Kagun however comments on how she is jumping ahead in the conversation, and should calm down for now.
VS The WorldEdit
The next time Maria and Freyja are shown, they are in the hospital with Kagun nowhere to be found, likely hinting that Kagun has finally been put to rest.
Named after the Icelandic saga character known as Bersi, Kihara Kagun wields the sword known as Whitting (ヴィーティング?), wielded by Bersi in his duel against Kormak. It is described in the saga as "a sharp sword, with a life-stone to it".
When in battle, the sword scatters when its owner is at a disadvantage, and amongst its shards, a miracle would occur, a spell that could accurately avoid damage and cause the sword to be sharper. When both are assembled, the sword's destructive power will increase exponentially. The sword appears a bluish laser sword several meters long that extends from Kagun's middle and index fingers. Its magic allows Kagun to nullify all fatal attacks and increases the sword's power every time he's attacked.
This may be based on the outcome of the battle between Kormac wielding the sword Skofnung and Bersi wielding Whitting. In the battle, Kormac drew his sword incorrectly, draining the luck out of his blade, and it chopped off the top of Bersi's Whitting, and the tip cut Kormak on the thumb. Therefore, Bersi won the duel as he had drawn first blood.
What's more, with his knowledge of the human body, Kagun could apply damaging techniques to his advantage, as what happened with the killer he attacked.
Being a Kihara and a former researcher, Kagun has an ample scientific knowledge, especially he is able to safely stop and restart a human heart.
Also, as other Kiharas, he is willing to use unorthodox and dangerous fight methods, like when he detonated a convex landmine hidden in his coat in order to kill Kihara Enshuu. He proclaims himself an anti-Kihara specialist.
Character Art DesignsEdit
Haimura's design of Kagun remains the same overall. Originally, Kagun had a black colored theme, and had unnecessary lines tacked on him, though this was later removed in the finished design.
- (When questioned why he ended his research from NT volume 4): "Even when I get the results, the price I had to pay doesn’t match."
- (To Oumi Shuri, ibid): "Don’t. You cannot defeat me with that. Oh, I wasn’t looking down on you. In fact, I’m saying that you have too much strength to kill me.”
- (To Kihara Byouri, ibid): "I worked hard for this moment. I have worked hard for this delightfully Kihara-like moment by reusing Kihara Enshuu as bait in order to defeat my target. I did the same thing you did regarding Kumokawa Maria and the others. I waited for the moment when the situation calmed down. You had your wheelchair, your leg assisting robot, that formation of your legs using Dark Matter, and that body. To be satisfied that I have killed you requires proof that all of your safety devices have been destroyed. Have you used up all your safety devices? Are you out of transformations? If so, I am quite glad. The chance to finish off Kihara Byouri has finally come my way."
- (After Kihara Byouri admits to having manipulated the boy Kagun killed, ibid): "I already knew the answer, but it still feels good to hear it from you. That trigger had more of an effect than you could have imagined. So that attacker was just another victim. I killed him as evil without thinking about it deeply enough. I sullied that victim of a child with the name of an attacker of young children and that label will never leave him. That is why I must at least carry out this revenge. As the two perpetrators of this wrong, this revenge will not be complete until one of us is defeated."
- (To Kihara Byouri, ibid): "I said it right from the beginning. I would take revenge for the boy whom you degraded into a murderer. I came here for this. In that case, victory wouldn't matter. You, who prompted that murderer, and me, who killed that murderer; once we continue to fight, my aim will be achieved."
- (To Maria before dying, ibid): "Sorry..."
- (To Othinus from NT volume 8): “This holistic esper and everything else are Marian Slingeneyer’s territory. I see nothing more I must do. Give me my next instruction.”
|Kihara Amata||Kihara Gensei||Therestina Kihara Lifeline||Kihara Nayuta||Kihara Kagun|
|Kihara Ransuu||Kihara Byouri||Kihara Enshuu||Kihara Yuiitsu||Kihara Noukan|
|Cendrillon||Saronia A. Irivika|