Karui

is a kunoichi of Kumogakure, and a member of Team Samui. The team was sent to Konoha by the Fourth Raikage to inform them that they would be taking care of Sasuke Uchiha and Akatsuki. She, along with the other two members of her team, are Killer Bee's students.

Personality
Karui seems to have a somewhat comedic-negative relationship with her teammate, Omoi. During their debut, they argued over the possible reasons that they could have been called by the Raikage. She assumed that he wanted them to get him more protein shakes. However, the argument started with Omoi implying that she is flat-chested in comparison to their teammate, Samui. However, like the rest of her team, she highly respects Killer Bee.

Karui is also quite outspoken and allows her emotions to come out, as she angrily yelled at Team Kakashi to allow the renegade Sasuke to run loose. She came to a violent point when she took out her rage on Naruto and beat him without hesitation.

Swordsmanship Specialist
In terms of fighting style, Karui relies mainly on swordplay, and thus would be considered a swordsmanship specialist. She and Omoi use attack combos together with swords, using slick, precise movements as they work well together. Karui is very strong, as shown when she punched Naruto hard enough to make him bleed instantly.

Senjutsu Training arc
In her first appearance, she and Omoi argued over the possible reasons that they could have been called by the Raikage. Omoi thought he was going to be scolded for putting mayonnaise on his potatoes; the argument started, however, with Omoi suggesting that Samui's back problems stem from her large breasts, something Karui doesn't need to worry about, cause of her being "flat chested."

Five Kage Summit arc
Later, after Naruto's victory over Nagato, Karui and her team were seen travelling to Konoha, when Omoi worried that, once they got there, a girl would fall for him and, once he had to leave, she would commit suicide out of loneliness. During that short argument with him, Karui threw a rock at him. While Omoi worried that she could have buried Konoha had she caused an avalanche, Karui angrily yelled that he overreacted too much. After they arrived at Konoha, they were shocked to find a giant crater in its place (caused by Pain's Shinra Tensei shortly before his battle with Naruto). Omoi blamed Karui for the crater being there, while Samui said they should ask someone for information on what had happened.

Karui and Omoi overheard Naruto and Sakura talking about Sasuke, so they attacked Naruto, Sakura and Sai. Later, they explained that Sasuke had attacked and captured their sensei, and that he is an Akatsuki member. Karui then insulted Sakura and asked her what Sasuke is to her, unable to find an answer to the question, causing Sakura to cry, but was stopped by Sai pointing out that they should not pressure and blame her. Later, Karui and Omoi attempted to get Naruto talking about Sasuke, but Naruto refused, not wanting to sell him out and cause chains of hatred. Wondering what to do with their hatred, Naruto told them to take out their hatred on him by beating him up, which Karui did. Karui continued beating up Naruto until Sai interfered. She then threatened to beat up Sai too, but was stopped by Omoi. Samui arrived, and asked Karui and Omoi to help her copy down all of the Leaf Village's information on Akatsuki and Sasuke. Once they left, Omoi wondered if Naruto was alright. Karui angrily told him to be quiet, through which Omoi could tell that Karui cared as well.

Karui is seen welcoming back the Raikage, Bee, C and Darui after the Kage Summit, and she is relieved that her master is safe.

Trivia

 * "Karui" means "light" or "non-serious" in Japanese, as a contrast to Omoi's name.