Karin

is a former subordinate of Orochimaru, presumably a former kunoichi of Kusagakure, and a member of the Uzumaki clan. She assisted Orochimaru in his experiments, and was left in charge of his Southern Hideout while he was away. She was later recruited into Sasuke Uchiha's group Taka, which was initially called "Hebi" at the time of its creation, as the sensor of the group.

Background
As a child, Karin lived in a small village that was burnt to the ground during a war. She was the only survivor and was completely unharmed. Orochimaru found her afterwards and asked how she survived, to which she answered that she could tell that huge groups of people were coming. Orochimaru then brought her to Otogakure, where she served as a jailer at one of his bases. Karin eventually took part in the Chūnin Exams that were held in Konoha, with her forehead protector stating her affiliation with Kusagakure. During the second phase, taking place in the Forest of Death, she lost track of her team-mates and was attacked by a large bear. She was saved by Sasuke Uchiha who was disappointed to find she had the earth scroll as well, but she was able to catch a good glimpse of him before he left. She remembered the smile that Sasuke gave her and fell in love.

At some point, she was involved in experimentations on Jūgo and Kimimaro. Her impressive healing abilities were studied by Orochimaru and Kabuto with the latter successfully being able to replicate it. Unlike the rest of Taka, Karin was genuinely loyal to Orochimaru, going as far as to refuse to release Orochimaru's prisoners and, in the anime, having them killed for speaking of his death, even after his defeat.

Personality
Karin has a fluctuating personality; she will appear tough and in control at times, to the point of being violent and critical, and at other times will appear highly flirtatious. She annoys Suigetsu Hōzuki, whom she attacks whenever he voices his general opinion of her. In the anime, she stated that she was attracted to men based on their chakra quality, and claims that Suigetsu's chakra disgusts her. Sasuke Uchiha's chakra used to dazzle her, but it now scares her, due to it getting colder and darker from his hatred. Naruto Uzumaki's seems to calm and dazzle her as well, making her feel comfortable and relaxed due to it being warm and bright, though she also became scared after sensing an evil chakra within him.

Karin is infatuated with Sasuke since they first met; when he saved her during the Chūnin Exams. In the anime, she has a flashback of when Orochimaru sends her to assist Sasuke in capturing a horde of escaped prisoners. There, she is captivated by the level of Sasuke's chakra and develops an infatuation with him. Karin's infatuation bordered on obsession to the point of fanaticism. For example, when Hebi was recuperating after Sasuke's battle with Deidara, Karin was planning to drug both Suigetsu and Jūgo and then "ravish" Sasuke's unconscious body and it was later revealed that she had kept one of Sasuke's sweat-drenched shirts. Karin didn't make much of an attempt to hide her feelings, frequently suggesting to Sasuke that they should spend time alone. Karin was very angry when the Fifth Mizukage flirted with Sasuke, and called her an "old hag" for it. Despite Sasuke's chakra becoming increasingly "darker", she still found him attractive. However, after he stabbed her in order to kill Danzō and tried to kill her, then even order Sakura to kill her to test Sakura's intent to join him, Karin stated that she no longer cares about him. Karin has also used other's perception of her feelings towards Sasuke to her advantage, feigning mental instability while imprisoned at Konoha to make the guards pay less attention to her. Upon her escape, she furiously beat Suigetsu after following Sasuke's chakra, but with Sasuke's apology and Orochimaru's suggestion, she found herself unable to stay angry.

Appearance
Karin has crimson eyes, fair skin, and the characteristic red hair of the Uzumaki clan which she wears in an unusual hairstyle: her hair is short and spiky on the right side, while longer and straight on the left side giving half her hair the appearance of being spiky and somewhat unkempt on one side, while the other side is neat and straight. She wears brown glasses, which have a serrated blade hidden in them, and her outfit consists of a lavender uniform that exposes her navel, short black shorts, and long black thigh high stockings with black sandals. Her chest, neck and arms are covered with bite marks that result from using her Heal Bite, and all of which are hidden by her uniform.

As she is allied with Hebi, Karin begins to wear a pouch around her midsection, and later a black cloak. When allied with Akatsuki, Karin wears an Akatsuki cloak with a hood instead of a high collar. After the fight with Killer B, Karin briefly put her hair in a ponytail.

Abilities
Karin has been praised by Tobi as being "useful" for her abilities. They were also the reason why Orochimaru took her with him after he found her. Despite being mostly a non-combatant, Orochimaru himself has referred to her as one of his good experiments, and had enough faith in her abilities to put her in charge of the Southern Hideout's prison, since her abilities made escaping impossible. These skills were later most predominantly shown during the Fourth Shinobi World War.

Sensory Perception
Karin possesses a unique sensory ability known as the Mind's Eye of the Kagura, which allows her to track any targets through their chakra signature. Noted by Kakashi as a particularly skilled sensor-type ninja, Sasuke goes on to state that her ability to sense chakra is unlike anyone else's. She can greatly expand her range to detect the presence of others, easily discern whether or not a specific individual are among a crowd, pick up chakra from long distances, and determine if targets are approaching her and how many or what species. She can also determine the size of a target's chakra reserve and potency, and even tell whether or not someone was lying through the fluctuations in that person's chakra made from dishonest emotions. She can also find out if an enemy is using a clone technique, and indicate if someone, including herself, is trapped in genjutsu. She can, similarly, conceal her own chakra from others. However, doing so will render her unable to use chakra, thus disabling her sensing technique.

Life Force and Chakra Prowess
As a direct descendant of the Uzumaki clan, Karin has a remarkably powerful life force. This grants her immense potential longevity as well as equally strong vitality. As noted by Kabuto, Karin also possesses a unique healing ability which seemingly stems from this powerful life-force. With this power, she not only has incredible regenerative capabilities, but can also heal others by letting them bite her and absorb her chakra. The potency of her healing chakra was enough to restore Tsunade's chakra reserves. However, it is dangerous for her to use that ability more than once a day, and as a consequence, she is left with permanent bite marks on her arms, chest and neck. She can also use this ability to heal herself by biting herself.

Similar to Kushina Uzumaki, Karin is also able to materialise Chakra Chains in combat. During the Fourth Shinobi World War she was able to use the chains to destroy parts of Guruguru's giant wooden statue.

Intelligence
Karin is quite intelligent. During Hebi's hunt for Itachi, she was able notice the Konoha shinobi's way of tracking them was by Sasuke's scent. From this, she quickly came up with a method of throwing them off Hebi's tracks, by tearing up Sasuke's sweat-soaked shirt and tying it to many birds and having them fly in multiple directions. She was capable of quickly deducing the basics of a complex technique such as Izanagi during Sasuke's battle against Danzō. She is also resourceful, as seen during her imprisonment, hiding a blade in the frame of her glasses as well as a lock-pick set within a portrait that she seemingly carries around with her, all the while putting up an act of fluctuating feelings for Sasuke in order to lessen the guards' sense of security on her.

Other Skills
Although she usually takes a supporting role in battles as an unorthodox type of medical-nin, she seems to have some competence in close-range combat which was seen when she tried to attack Danzō Shimura to save Sasuke Uchiha, and also when losing her temper from Suigetsu's taunting.

In the anime, she was also seen using the Mystical Palm Technique to heal Sasuke, although it appears she is not as skilled with the technique as medical-nin are.

Itachi Pursuit Arc
Sasuke recruited her as a member of Hebi. While Sasuke admitted that she might be troublesome sometimes, he also noted that her special abilities made her useful. While Sasuke tried to recruit her, she tried to seduce him. Once the team was completed, Sasuke sent Hebi out in multiple directions to try and locate Itachi Uchiha. While on the search, Karin passed Sakura Haruno, although the two did not acknowledge each other. After Deidara's suicide explosion, the rest of the team regrouped and took Sasuke to an inn to recover. When Karin went out for supplies, she sensed the Eight Man Squad approaching, and warned the team. It was her plan to use Sasuke's old clothing as a means to distract the squad from catching them. When they finally got back on Itachi's trail, Karin stayed behind with Suigetsu, Jūgo, and Kisame as Sasuke went ahead to battle Itachi.

Invasion of Pain Arc
Hebi, now renamed Taka, later began working with Akatsuki. They were sent to Kumogakure to capture the Eight-Tails' jinchūriki. When they found him, Karin stood on the sidelines and watched the others fight Killer B. When Sasuke was mortally wounded fighting Killer B, Karin immediately rushed to pull the dying Sasuke out of the fight, as Suigetsu and Jūgo kept Killer B busy. As she pulled the swords out of Sasuke's body she exposed her right arm, riddled with numerous bite marks. She then told Sasuke to bite her arm, and as he did, her Heal Bite healed his wounds.

As Killer B got bored and attempted to leave, Karin used her Mind's Eye of the Kagura to locate him. Killer B then used his demonic chakra to charge at her, Jūgo, and Suigetsu, but Jūgo rocketed them away to safety. After Sasuke was yet again critically wounded by Killer B, Karin insisted on reviving Sasuke again. She was stopped by Jūgo, who claimed she didn't have enough chakra to save Sasuke again, so Karin watches as Jūgo transfers his flesh to Sasuke to heal him. When Killer B fully transformed into the Eight-Tails, Sasuke used Amaterasu to quell it. Karin quickly moved all of her team-mates out of the way of one of Killer B's tentacles, but this resulted in her being hit by one, and some of the black flames spread to Karin's cloak. Sasuke used his Mangekyō Sharingan to put them out. Karin was carried to safety by Jūgo.

While the team was recovering, Karin briefly put her hair in a ponytail. She noticed that something was wrong with Sasuke, but as he brushed it off, she detected J|an enemy outside their base, which Sasuke and Jūgo went to investigate.

Five Kage Summit Arc
After Taka recovered, they moved out for Konoha. Along the way they are stopped by Tobi, who convinced Sasuke to go after Danzō Shimura at the Kage Summit. When they arrived in the Land of Iron, they decided to wait until the meeting was over before they attack. Zetsu soon revealed their presence and the Kage mobilise against Taka. When the battle got under way, Karin noticed that Sasuke's chakra was now darker than when in his cursed seal level two state.

When the Fourth Raikage arrived, he instructs C to locate and eliminate Karin, Taka's sensory ninja. Karin hid her chakra to avoid detection, and once C was defeated by Sasuke she again began to look for Danzō's location. By the time Sasuke is able to elude the Raikage, Karin had found Danzō. She informs Sasuke that Jūgo and Suigetsu are still alive, but he said to leave them and had her lead him to Danzō. Danzō fled as soon as they arrived, and Sasuke was forced to fight the Fifth Mizukage and the Third Tsuchikage before he could follow. During the brief confrontation Karin grew concerned with Sasuke's deteriorating chakra levels. When his chakra signature disappeared, she broke into tears, believing him to be dead, with the Tsuchikage turning his sight on her.

Tobi soon appeared with Sasuke in tow before he sent them both to a different realm so she could heal his wounds. He later returned and released them in front of Danzō so that Sasuke could fight him. Karin observed the battle and tried to determine how Danzō was able to survive a series of apparently fatal injuries. She immediately ruled out genjutsu or a clone technique, and eventually noticed that the Sharingan embedded in Danzō's arm closed one by one as the battle progressed. Coupling this observation with frequent descents in Danzō's chakra levels, she learned the secret of his technique. She told Sasuke about it and advised that he keep his distance until Izanagi expired.

Once Sasuke mortally wounded Danzō, Karin healed his injuries. Danzō then took Karin hostage as he refused to die. Karin called to Sasuke for help, but Sasuke stabbed her through the chest in order to pierce Danzō's heart. Sasuke simply commented that, if she can be taken hostage so easily, she was now only a burden to him. Karin collapsed and Tobi suggested that Sasuke finish her off since she had some knowledge of their plans. As Sasuke walked towards Karin, she has a flashback of her first encounter with him at the Chūnin Exams and remembered his smile. She took one last look at Sasuke, wishing to see his smile one more time, before he was about to kill her, but he was interrupted by the arrival of Sakura.

Sakura insisted that she wanted to be with Sasuke no matter what, leading Karin to realise that Sakura too loved Sasuke. Sasuke ordered Sakura to prove her loyalty by killing Karin. This, however, was a lie to make Sakura drop her guard. As Sasuke prepared to kill Sakura, Karin managed to mutter a warning, before Kakashi Hatake arrived to counter the attack. After it became clear that not even his words can alter Sasuke's motives, he ordered Sakura to take Karin away from the area and heal her enough to talk. While still barely conscious, Karin looked up at a sobbing Sakura and pleaded for her to hold in her tears. A tear fell down Karin's face as she sensed a further change in Sasuke's chakra, stating that Sasuke is no longer the person that Sakura once knew. As she asked Sakura what she will do, Sakura didn't respond and, emotionally unstable, returned to the fight despite Karin's warnings.

Later, when Sasuke prepared to fight with Naruto, Karin, sensing that Sasuke is going to over-exert himself again, dwelled on the fact that she was only able to heal him a little from his earlier skirmishes, before catching herself in that thought; in light of the fact of everything that Sasuke had done to her, Karin decided to herself that she was now done with Sasuke. After Sasuke left, Kakashi told her that she was coming with them to Konoha; Karin resigned to her fate as she had no choice, being warned by Kakashi not to try anything. As Karin left with them, she made a special note of Naruto's character, apparently hearing of him before.

Confining the Jinchūriki Arc
Later, she is interrogated by Ibiki Morino in Konoha to get information on Akatsuki, Sasuke and Kabuto Yakushi. Though she initially wove a tale in which she was a victim of both Orochimaru who she claimed had forced her into hard labour and Sasuke who had unreasonably demanded too much from her, Ibiki saw through it immediately and Karin switched tracks, insisting to be fed a bowl of deep-fried pork cutlets before she would talk. While the other two fussed over making preparations however, Ibiki remained stone-faced. Karin later noted that all the people in Konohagakure seem to all be cheerful and warm, just like Naruto.

Shinobi World War Arc
Having been jailed some time after the interrogation, Karin talks to a portrait of Sasuke, first stating that he was cool and then immediately throwing down the picture and cursing him for trying to kill her. This erratic behaviour seemingly has been going on for a while, bewildering the guards. This, however, is revealed to be a ruse, as Karin uses the guard's distraction to pry open the portrait with a hidden blade in her glasses, revealing a lock-pick set.

Ten-Tails Revival Arc
After escaping from the jail, Karin noticed Sasuke's chakra in the village and couldn't believe that it would be him. She followed the signal just as Taka, Orochimaru and the Hokage prepared to leave for the battlefield, attacking a fleeing Suigetsu over what had happened to her. Sasuke's apology for attacking her was met with a mix of anger and giddy appreciation as she noticed Orochimaru among the group. In the end, she found herself unable to stay angry at Sasuke and forgave him.

Karin, Suigetsu and Orochimaru later arrived at the battlefield where the five Kage were, with the latter commenting on Tsunade's condition. Karin was then ordered by Orochimaru to assist Katsuyu in healing Tsunade by having the Fifth bite her. However, Karin hesitated because she didn't like anyone other than Sasuke to benefit from biting her. Suigetsu then proved Karin was really interested in Sasuke and pointed that she had already had many bite marks on her even before meeting with Sasuke. This then lead to another brief spat between the two, which was almost immediately stopped by Orochimaru after he had threatened them with his snakes. While healing Tsunade in that state, Karin noted that if Tsunade did not stop biting her soon, she herself might turn old. She later departed with Orochimaru and Suigetsu to the battlefield. Upon arrival, Karin is almost immediately consumed by her obsession with Sasuke, so much so that she dismissed Suigetsu's observation of the Shinju before catching herself and agreeing with him that the recovery of the shinobi was paramount.

Return of Madara Arc
While Orochimaru and Taka are hiding from Guruguru's giant Wood Release and thinking up a strategy, Karin became distraught upon sensing Sasuke's critical condition, figuring that with no intervention, Sasuke will die. Determined to save Sasuke, Karin joined the battle, manifesting Chakra Chains to destroy parts of Guruguru's statue. After being impaled by the Wood Release: Cutting Technique, she bit herself in order to heal. Grabbed by Jūgo who removed the stakes, she noted that she was okay, but feared they were too late as she could no longer sense Sasuke's chakra. As they rushed towards Sasuke's location, Karin sensed a chakra of someone she didn't recognise and alerted her group. Moving even faster as she disregarded her own well being, she rushed to Sasuke's aid.

Upon reaching Sasuke, Karin discovered that the mysterious person was Kabuto, whose various modifications to himself made his chakra signature too different for Karin to recognise. Seeing Kabuto merging his being with Sasuke, she quickly became convinced Kabuto harmed Sasuke. Kabuto calmly explained that he no longer desired Sasuke, rather he was healing the young Uchiha. To her shock, she began to sense Sasuke's chakra. Kabuto explained that his experience under the effects of Izanami made him rediscover himself and sought to correct his mistakes.

Video Games
Karin's fighting style differs in her video game appearances:
 * In Kizuna Drive, Karin uses her Mind's Eye of the Kagura technique to avoid enemy attacks, and can enter the same Medical Mode as Sakura Haruno and Ino Yamanaka.
 * In Shinobi Rumble, Karin is shown to use senbon, and she attacks her opponents with them after detecting them in a radius of her Mind's Eye of the Kagura technique.
 * Karin's techniques in Ultimate Ninja Heroes 3 are focused on her Mind's Eye of the Kagura technique, allowing her to avoid enemy attacks at a close and long range. If Karin uses her Ultimate Jutsu on Sasuke in "Naruto Shippūden: Ultimate Ninja Heroes 3", Karin blushes, and stares in awe at Sasuke's beaten up body right after she finishes her technique and says "Oh yes". "Student Sasuke" may be fought for the same effect.
 * In Ultimate Ninja Storm 2, Karin's techniques are more focused on her personality, as she sprays poisoned perfume that she carries in the pouch on her back and slaps opponents with explosive tags. When fighting Sasuke, Karin's entire demeanour changes, and she frequently remarks and swoons over him while fighting, and her techniques and Awakening mode are modified.
 * In Dragon Blade Chronicles, Karin is shown to have a diary; a black book that she keeps in the pouch she wears on her back and has decorated with pink hearts. She tells Sasuke that she could write about him in it if he insists.

Trivia

 * Karin's name is made up of the kanji for and.
 * According to the databook(s):
 * Karin wishes to fight Suigetsu.
 * Karin's hobby is collecting perfumes. It is amusing to note that the Japanese word for perfume is written with 香 — the first kanji in Karin's name — and 水 — the first kanji in Suigetsu's.
 * Karin's favourite food is okonomiyaki, while she dislikes gyōza.
 * Karin's favourite phrase is.
 * Karin has completed 50 official missions in total: 25 D-rank, 16 C-rank, 7 B-rank, 2 A-rank, 0 S-rank.
 * According to the Second Hokage, Karin has a good amount of chakra.
 * Both are attracted to the "dark" team member (Rin by Kakashi and Sasuke by Karin)

Quotes

 * (To Sasuke) "If you really want me to Sasuke… I will follow you."
 * (To Sasuke about Suigetsu) "I hate Suigetsu always running his mouth."
 * (To herself about Sasuke) " …I just wanted… to see that face once more…"
 * (To herself about Sakura) "You're the enemy… I don't want to sympathise with you… so… so don't… don't cry like that in front of me…! Damn it…"
 * (To herself about Sasuke) "Sasuke… I may have healed you a little, but this is too much… actually… forget it, I'm done with you."