Karin is voiced by Ali Hillis in the English Version and by Kanako Tojo in the Japanese Version.
Karin was once a ninja from the Hidden Grass Village. She participated in the Chunnin Exams and met Sasuke Uchiha for the first time when he saved her from a bear, falling in love at first sight with him. Sometime during that year, Karin's village was burned down by enemy ninja and she was founded by Orochimaru and he made her one of his prison guards.
Karin was first introduced as a prison guard of Orochimaru, and she was chosen by Sasuke to help him as a member of Hebi. While Sasuke admitted that she might be troublesome, due to her attempts to seduce him when made the offer, he knew her chakra sensory would be useful to him. While Sasuke battled Itachi, Karin used Sasuke's old clothes to sent the Eight Man Squad sent after Sasuke in circles so there would not be interference.
After Sasuke defeated Itachi and found out the truth about the village elders ordering his brother to slaughter their clan, Sasuke reformed team into Taka and ally themselves with the Akatsuki to destroy Konoha and avenge Itachi. While Taka was sent after the Eight Tails Jinchuuriki Killer Bee, the team successfully found the jinchuuriki and battled with him to the death. Karin used her Heal Bite Jutsu to help Sasuke continue the fight. The team managed to defeat Killer Bee and take what they thought to be him back to the hideout.
However, on the way to Konoha, Karin learns the "Killer Bee" they captured was a clone created from a part of Gyuuki the Eight Tails. From there, Taka is sent to the Land of Iron to assassinate Danzo Shimura while he attended the Kage Summit. After helping Sasuke battle the Fifth Mizukage Mei and the Third Tsuchikage Onoki, Karin is brought into Tobi's subspace to heal Sasuke before he battles Danzo. Through staying on the side lines for most of the fight, Karin ended up in the old man's clutches to keep Sasuke from dealing the death blow.
Though she begged Sasuke to help her, Karin is horrified when use his Chidori Spear to fatally wound Danzo in the heart by running it through her. Betrayed and in horrific pain, Sasuke cruelly told Karin that if she is slow enough to let herself get easily taken hostage, then she is useless to him. Once Danzo is dead, Tobi told Sasuke to finish Karin off as she knows too much to be left alive. As Sasuke approached her, Karin thought about her first meeting with Sasuke during the Chunnin Exams and wished that she could see that smile on his face one last time. However, Karin is saved by Sakura at the last minute.
As Kakashi battles Sasuke, after nearly getting herself killed, Sakura heals Karin's injuries. Though barely conscious, sensing Sakura's sadness yet not wanting to symphaze with an enemy, Karin tells her that the Sasuke they both knew is dead and warns her against returning to the fight. By the time Sasuke battles Naruto, recapping everything she did for him and how he returned the favor, Karin decides to no longer help Sasuke. Soon after, sensing Naruto's chakra to be the polar opposite from Sasuke's, Karin is taken to Konoha for interrogation under Ibiki Morino of what she knew. However, Karin is hostile throughout the interrogation as she is placed in jail soon after. As the Fourth Great Ninja War commences, faking a hissy fit over Sasuke betraying her, Karin arranges the means for her escape. She later met up with Sasuke, where after Sasuke had learned the truth about Konoha's founding and had given up on revenge he simply apologized to her for his previous actions of nearly killing her. Karin quickly forgives him and realizes she can't stay angry at him after all.
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.
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. Eventually, Kabuto succeeded in healing Sasuke, who quickly returned to his feet and was ready to resume the battle. Karin and the others present there besides Tobirama were later caught in Madara's Infinite Tsukuyomi.
After Naruto and Sasuke seal Kaguya away and settle their differences, Karin alongside everyone else was released by the Infinite Tsukyomi with the help of Naruto and Sasuke. Karin would later resume her work as Orochimaru's subordinate while Sasuke returned to Konoha before going on a journey of redemption. After Sasuke married Sakura and they were expecting their first child while traveling together, Karin served as a midwife when Sakura went into labor and helped her give birth to her and Sasuke's daughter, Sarada. Although she seems to still have deep care for Sasuke, Karin told Suigetsu that all that matters to her is that Sasuke is happy with his family, even admitting she is friends with Sakura and is fond of Sarada.
- Aside from Sasuke, she is the only member of Team Taka to meet all members of Team 7.
- Her name means "perfume" (香).