In his old form as a Shinja Impurity, Kamui was larger and had big spikes on his shoulders, a big horn on his head, and a kuji-kiri on his chest.
After gaining more power, he attained a new form which resembles that of a young man. He has dark skin and wavy shoulder-length, light-purple hair. His left eye is completely black with a red pupil and cracks on both upper and lower part of his eye, while his right eye is gold-colored.
Kamui wears a black tailcoat with white stripes designs which is left opened to expose his torso, whilst similarly colored pants which expose his thighs in the anime. He is always seen barefooted.
After gaining extra power from Benio during his fight with Kaguya. Kamui eyes changed to be gold and his hair grew to reach past his shoulders. In serious battle his abilities changed so that his body gains some form of armour or clothing similar to a Guardian with Mystic Spell Equip or Impure Death Equip of a higher ranked Basara.
After the timeskip, Kamui has changed his attire to that of a black cloak.
Kamui is calm yet ruthless, having no mercy for humans or other creatures, he does not care about their feelings, comparing them to mere insects. Though, he tends to often let his opponents choose the death of their preference, and always gives them ten seconds to decide. He seeks entertainment by fighting humans without caring about which side (Human or Impurity) will be destroyed, and loves humans because, despite the fact that they are weak, they continue to passionately struggle and strive for their lives and desires against forces stronger than them.
He also likes fighting strong beings and loves life-and-death battles. If his preys are being snatched away by other opponents, he is willing to give them power as shown when he gave Benio two legs after her own were ripped off. Initially this isn't an act of kindness, this is just to make sure he will have an interesting battle with them afterwards. However, Kamui feels he may have another reason for helping Benio that he can't discern.
After interacting with Benio, he seemed to grow more human-like, as he was lost to the various subtle feelings to Benio. These feelings only grow after saving a human child and as their journey progresses, leading to Kamui's change of heart. After the battle with Kaguya, Kamui seeks atonement for his crimes, wishing to live for the day the Twin Stars can exorcise him.
After his journey with Benio, it is implied Kamui has stopped killing humans.
When meeting Rokuro and Benio again, he challenged Rokuro for Benio.
Years ago, Kamui, while he was still a Shinja, was confronted by Benio's parents. He was able to defeat them, and grabbing them, he had their eight-year-old daughter choose to pick which parent he would spare, giving her ten seconds to decide. However, she was too scared to pick, so Kamui asked her parents whether he should spare them or their child giving them ten seconds to decide. Without hesitation, they both stated he should spare their child and Kamui killed them as promised. This encounter made Kamui remark that of all the people he made decide, they were the rare exceptions as they did not try to save themselves.
Years later, Kamui gained a new form and went about Magano looking for the Twin Star Exorcists killing any Impurities or Exorcists in his path. Kamui then confronts Benio who was about to kill three Impurities, he easily destroys them knocking her down in the process. He proceeds to question her over where the Twin Star Exorcists are. He threatens to kill her if she doesn't answer giving her ten seconds to pick. This causes her realize who he was. Kamui (not remembering her at the time) was surprised that Benio remembered him as she stated she has been searching for him years for what he did in the past and attacks him only for to knock her aside and subdue her by stepping on her head.
Kamui tauntingly asks Benio if she remembers every face of insects she squashes and prepares to kill her but he is punched by Rokuro whose his strength interests him as does his Impurity arm. He watches as Benio informs Rokuro of his status as a Basara. When an Impurity he fought earlier attacks him, the two exorcists take the chance to briefly retreat and Kamui kills the attacking Impurity. He soon wonders where the two exorcist are until Rokuro returns and battles him managing to put up a better fight than Benio. Kamui states he has never been this entertained and gives Rokuro the option of continuing their fight or letting him go since he potential giving him ten seconds. Rokuro questions him over this as Kamui explains his habit of enjoying to see what options they will choose and seeing whether they will turn on their comrades to save themselves while very few have choose to save others. Mentioning this makes Kamui remember Benio from six years ago, as he explains to Rokuro over what happened to her parents.
When Rokuro asks how he could do that in front of a child and how he can be so corrupted, Kamui casually remarks that's what makes him an Impurity. Rokuro then angrily punches him and blows him away with a series of blows. An amused Kamui mentions that Rokuro might be a person who might make him use a cursed talisman. With the talisman, his legs take on a new form and with a leap he attacks Rokuro who tries to block but fails as Kamui kicks Rokuro aside. Kamui explains the power of his talisman before noting what shape Rokuro is in. He tells Rokuro that he went through the trouble of activating his power and tells him to entertain him before moving to kill him before Benio returns and attacks him making dodge. Kamui tells her to step aside as fighting her is boring and when she attacks him again he notes on her improved fighting before he knocks her away.
He then watches as the two exorcists then combine their powers which makes Kamui realize they are the Twin Star Exorcists. He leaps at them telling them to entertain him some more before they fire an attack at him.
Kamui emerges with half his leg destroyed, he remarks he was naïve, as he discovered Rokuro and Benio were the Exorcists he was looking for. They question his knowledge over that as he remarks about the prophecy of the Miko destroying all Impurities has been spreading news amongst the Impurities who want the exorcists wiped out. He tells the two he does not care whether the humans or Impurities are exterminated only if he is entertained.
He states although he should kill them before the Miko can be born, he decides not to as they have entertained him more than anyone else has and decides to leave telling them not to be defeated by anyone and to get stronger so that in their next meeting he could use only half of his power. He states they are now his prey and he looks forward to fighting them again or tells them they could have Miko so he can battle it. With that, Kamui leaves the area.
Later on, having recovered his leg he witnesses Rokuro and Benio's battle with Yuto Ijika from afar. He then arrives on the battlefield where he saves Benio from a swarm of Impurities remarking they are having fun without him. He questions the wounded Benio over whether she wants to continue fighting and if she wanted the power to do so. She questions him over this as he tells her he can give her wounded legs Kegare powers legs like Rokuro's arm.
Benio asks him why he would do that and what his gain is from that as he tells her that its for pleasure as he enjoys fighting strong people and seeing their potential to get stronger so he can fight them again. He remarks the way her brother Yuto is flaunting his strength is irritating and he gives Benio ten seconds to decide. Before he can finish counting, she tells him she wants the power to stop her brother and the power to kill him. Amused by her answer, Kamui tells her if she turns into an Impurity he will take responsibility and kill her himself. With that he proceed to use a spell on her legs enhancing them with Impurity powers. He is shocked that even though it is corrupted power it is beautiful.
After getting this new power, Benio introduces herself to Kamui who in turn gives his name. To his shock, Benio thanks him for his actions but warns him that one day she will use this power to kill him. Laughing at this, Kamui tells Benio if her threat ensure a good fight in the future he'll be waiting.
He watches in amazement as Benio proceeds to attack and overpower her brother who he notes was putting up a front about not being injured by Rokuro to save face. When Benio collapses, Kamui notes that time ran out for the Kegare powers and watches as she is tortured by Yuto until she is saved by Rokuro who receives a hole in his chest but it is healed and he gets new powers.
Kamui watches as the newly powered Rokuro challenges and soon defeats a transformed Yuto until he collapses. Kamui watches as Rokuro and Benio rest on the ground before Shimon Ikaruga appears and the two lock eyes before Kamui leaves the area.
Two years later, while Benio was walking a group of Impurities surrounded her, due to losing her power she was utterly helpless. However, Kamui appeared and slew them all with ease before telling a shocked Benio her current state was pathetic. He further derides Benio by bringing up her vow to kill him and now her attempts to ask him for help as shameful becoming annoyed that he showed in interest in her as an opponent before leaving.
Afterwards, he finds Benio again running from Impurities and becomes impressed with her resolve of not giving up. He alerts her of his presence by telling her that he came because he learned that the strongest Basara Chinu was on the mainland before killing the Impurities attacking Benio. He then tells her that her enchanted powers are not actually gone and if she does as he says he'll take her to Chinu to get her powers restored. As Benio asks Kamui why he is helping her, she gets the same old answer: because he likes fighting strong beings.
Kamui asks Benio to take him to Rokuro as soon as her enchanted powers are restored and adds that fighting both of them is the ultimate fun he's been seeking.
Afterwards, he sends Benio back to reality, telling her to get ready and pack as if she were never coming back to the town, then come back to the same place in half an hour. Benio protests, not wanting to go with him, but Kamui points out the fact that she isn't even able to exit Magano alone, so she probably won't be able to regain her powers on her own either. Kamui also states that if she isn't back in half an hour, he will have no reason to remain on the mainland, implying that he has only come for her.
After Benio returns, the two depart on an almost two months long journey to find Chinu. They mostly walk without saying anything because none of them feels the urge to initiate a conversation. At night, Kamui sends Benio back to reality, to take care of her meals and sleep, as well as other needs.
Being a top ranking impurity, Kamui is shown to often behave just like an ordinary human, as he needs meals, excretes waste and requires sleep when tired.
As their journey continues, Kamui and Benio come across a child who has been dragged into Magano. Seeing that Benio wants to fight the impurity attacking the child, Kamui tries to stop her, to no avail. He ends up killing the said impurity himself and sending the child back to reality. He tells Benio to hurry up and throw the child out of Magano, as he considered the mere act of saving him to be worthless.
However, when the child thanks him for his actions, Kamui is once again shocked, not being able to comprehend good. He remembers how Benio cried when she was on the verge of dying, and how she thanked him when he gave her power, just like the child did, but he still doesn't seem able to understand human behavior.
After parting ways with the child, the two continue their journey. As they are passing an old bridge, Benio falls into a dirty river. At first, Kamui thinks that she is an idiot, but then, he suddenly looses his sense of self, at the sight of a vulnerable, soaking wet Benio. He then rushes towards her and begins to rip off her clothes. No matter how much Benio struggles and punches him, Kamui doesn't give any sign of coming to his senses. What wakes him up, however, is her sobbing and tears.
Kamui pulls back, not being able to understand what's gotten into him. He is then confronted by an enraged Benio, who calls him an animal and vows to kill him once again. At that, Kamui shows a rather sad expression, telling Benio that she has no choice but to survive until that time comes.
After this incident, Kamui did nothing but walk in silence, with Benio behind him, until they reached Chinu.
Chinu acted friendly to Benio, however she ordered Kamui to act as a guard to Benio's transformation ceremony. Kaguya suddenly emerged and Kamui confronted her.
Four years later, Kamui has gotten stronger and has become the third strongest Basara and be recognized as a grave threat to the exorcist union.
Powers and Abilities
- Enhanced Enchanted Power: As a Basara, Kamui has great power that outdoes the power of a regular Impurity or Exorcist. Arima states that Basara's power is comparable or stronger than The Twelve Heavenly Commanders. After four years, his threat level has risen to that of the third strongest Basara.
- Enhanced Physical Strength: In his humanoid form, he has been shown to have tremendous strength easily dispatching several Impurities or exorcists in his path. When faced with a powerful exorcist like Benio Adashino, he was able to break Benio's leg with just a flick of a finger and destroying her holy sword with just a hand raise.
- Enhanced Physical Endurance: He possesses great durability shown when took several blows from Rokuro Enmado and his kegare arm. He was also not fazed by having half his leg destroyed as a result of taking a combined attack from Rokuro and Benio.
- Regeneration: He seems able to regenerate as he was able to regain his leg after it had been destroyed by Rokuro and Benio using Resonance.
- Impurity Corruption Spell: Kamui is capable of granting Impurity powers to exorcists as shown when he performed a spell that gave Benio's wounded legs powers like Rokuro.
- Impure Death Equip: As a Basara, he possesses a cursed talisman to use an impure enchanted gear that's contradict to the the exorcist enchanted gear.
- Danshin Angya (断神闇脚 Danshin Angya?, lit. God of Judgement, Legs of Darkness): Using his talisman, Kamui enchants his legs and they turn into black-purple with thorn legs that increase his strength and speed tremendously with an ability that his attacks will transfer all the shock to his opponents' entire body thus cannot be blocked.
- Beast Form (Anime only): Kamui is shown to transform into a purple beast after he was amazed by how powerful his opponent is.
Kamui's most imperative adversary. Having to give a young Benio an impossible choice to spare the father or mother only to crush them both, changing Benio's life forever. Several years later, to his surprise the once timid girl is now one of the Twin Star Exorcists. Watching the battle against Yuto, Kamui offers the incapacitated Benio to have her legs replace with impurity. Encountering Benio again to his shame that she lost her enchantment abilities, refusing to waste his time helping her. Later he desides helping Benio is worth the trouble and the two go on a journey to find the Chinu, the first impurity, though Kamui can't understand why he thinks Benio is worth the effort. During the fight against Kaguya, Kamui realizes the reason he is so fascinated with Benio is that he has come to care for her unconditionally. This causes him to have a change of heart and question what it means to be an impurity. Realizing the harm he has caused, he contemplates dying only for Benio to talk him out of it, convincing him to live and atone for his crimes while waiting for the day Benio will exorcise him. It is implied he has stopped killing humans following his journey with Benio.
Not impress at first, Kamui thought Rokuro's style in exorcising was annoying then his opinion changed when he witnessed his impurity arm. Kamui was delighted that he used his talisman but disappointed that Rokuro couldn't handle it after being knocked back. However, when Rokuro and Benio's combined enchantment got him to acclaim them.
Determined to improve his strength, he found Chinu but learns that her status as the "strongest impurity" was just a exorcists' facade for the fact that she is the first impurity.
- His hobby is asking humans for their decisions.
- In the anime, his name is given on his introduction while in the manga it is in his second appearance.
- In the anime, he is shown have green markings on his old form, implying he might have been an impurity corruption.
- Kamui feels no shame in doing inappropriate things in front of others, such as when he pulled his pants down and urinated without a warning while Benio was behind him.
- He is the youngest Basara but has evolved faster than others to appear human, appearing similar to the eldest members- Chinu and Sakanashi due to his golden eyes.
- "Seriously, those humans. They don't know when to give up, do they? How many times is this now? Give me a break."'
— to himself
- "How about you? Do you remember the number and faces of all the ants you've ever stepped on?"'
— to Benio
- "A quick and easy death, or a slow and horrible death. Which would you like? You should choose the death of your preference. I'll wait while I count down from ten."'
— to Rokuro
- "I like you humans because you're weak. You weak humans, in your own weak ways, struggle and squirm... and you challenge me with a burning passion."
— to Benio
- "If people could get stronger by crying, life would be pretty easy."
— to Benio
- "Fighting both of you is the ultimate fun I've been seeking."'
— to Benio, about the Twin Stars
- The name Kamui means "god" (神) (kamu) and "prestige, uthority," power, dignity (威) (i).
- Twin Stars Exorcists Manga: Volume 13.