Kurenai Yūhi

Background
Kurenai Yuhi is the Jonin in charge of Team 8, which consists of Kiba Inuzuka, Shino Aburame and Hinata Hyuga. Her team specializes in tracking. Relatively little is known about her, other than the fact that she graduated from the Academy at the age of 9, took the Chunin Exam and became a Chunin at the age of 13, and that she only became a Jonin recently. The anime expands on her background slightly, explaining that she had come to the village at a young age with a natural talent for genjutsu.

Personality
While she has a close bond with all of her students, she seems to especially favor Hinata. Kurenai knows how Hinata is viewed by her father, even though she is technically the heiress of the clan since she is the oldest child. She is also somewhat aware of her student's tremendous infatuation with Naruto Uzumaki. When Hinata tries to offer Naruto some medicine after his fight with Kiba, it is Kurenai that convinces him to take it. Her personality is unyielding, honest, and simple. She also says she is a "sexy big sister type."

Hints throughout the series also suggest that she has a romantic relationship with fellow Jonin Asuma Sarutobi, though neither will admit to anything. The two tend to be seen together often, so they clearly enjoy each other's company, and Kurenai blushed on one occasion when Kakashi Hatake more directly suggested a connection between the two. Late in the manga there is a flashback of Asuma buying her flowers and lying to Ino about it while blushing. Shikamaru plans to tell her specially about Asuma's death, and she breaks sobbing at the news.

Chunin Exams
During the Chunin Exam, Kurenai watches her pupils from the sidelines. After Shino's battle, she comments on how it suddenly got cold in the room, in reference to his rather unmerciful defeat of Zaku Abumi. During Kiba's fight with Naruto, she thinks to herself (and to Kakashi) that Naruto can't possibly beat Kiba, only to be surprised over and over as Naruto takes everything Kiba throws at him. During Hinata's fight with Neji Hyuga, she remembers the terrible relationship Hinata has with her father. She also notes the stark contrast between the current Hinata, who refused to give up, and the former Hinata, who would give up easily. When Neji is sent into a blind rage by a comment of Hinata's, she helps stop him along with every other Konoha Jonin present, except for Asuma.

Sand and Sound Invasion
Kurenai wasn't seen in the scenes involving the invasion of Sunagakure, and Otagakure, but it is assumed she, like the rest of Konoha's ninjas fought off the invaders.

Return of Itachi
When peace was restored among the villages, Kurenai and Asuma were seen at a dumpling shop by Kakashi Hatake. When Kakashi commented them on this, noting how friendly they are to each other, implying some form of romance, Kurenai blushes and protests at this, saying that it was Anko that wanted the dumplings. Asuma changes the subject quickly by asking Kakashi why he's there, and notes that Kakashi doesn't like sweets.

Afterwards, Kurenai and Asuma discover the Akatsuki members, Itachi Uchiha, and Kisame Hoshigaki, and had a brief battle with the duo. Despite Kurenai's natural genjutsu skills, her Demonic Illusion: Tree Bind Death was easily reversed by Itachi's Sharingan, causing the latter to mock her for her unexperience with genjutsu compared to his Sharingan. Before they could be finished off, Kakashi arrives to save them, only to be caught in Itachi's Tsukiyomi, and then be saved by Might Guy.

Appearence in Filler
She has a short appearance during the Mizuki Strikes Back arc, in which she and Asuma attempt to interrogate Mizuki. Kurenai doesn't have any significant roles until a much later arc, which covers a small incident in her past with an extremely talented genjutsu user. The girl, named Yakumo, is the heir to the Kurama clan, which specializes in genjutsu. She has a kekkei genkai ability that enhances her genjutsu to an almost ridiculous extreme, allowing her to literally kill people with genjutsu. Kurenai sealed Yakumo's kekkei genkai in a ceremony similar to Kakashi's sealing of Sasuke's cursed seal, but it didn't. After Yakumo resurfaces and causes lightning to strike the Hokage mansion (an illusion, but one so powerful that everyone in the village is convinced it happened), Kurenai requests to be separated from her team to deal with Yakumo.

In a flashback, the Third Hokage describes both Yakumo and Kurenai as "untrained genjutsu users", noting their inherent talents in genjutsu. Yakumo, having physical difficulties training as a ninja, was put under the care of Kurenai. She had hoped to be like Rock Lee; she wanted to become a ninja despite her apparent handicap. Kurenai, unlike Guy, discouraged this attitude because of the kekkei genkai ability she would be forced to lean on.

On her way to visit Yakumo, Naruto confronts Kurenai about her involvement with Yakumo. To evade further interrogation by Naruto, she uses Demonic Illusion: Tree Bind Death, leaving him incapacitated until Sakura, Guy, and team 8 arrive. As she approaches the Yakumo's cabin, she becomes trapped in a rebel's genjutsu, revealing afterwards that she had trapped her attacker in her own genjutsu. She discovers that these attackers are in fact Kurama clan members intent on kidnapping Yakumo. Seeing that her opponents are also genjutsu users, Kurenai notes that "there's no way [she] can lose." From this point, she and the opposing ninja basically fight with nothing but Demonic Illusion: Tree Bind Death, using variations on the standard theme of the jutsu. Kurenai ends up successful until the final encounter, where she is caught off guard and cut by shuriken. The blood reveals her presence to the enemy, who is the temporary leader of the Kurama clan, Unkai, allowing him to defeat her.

Kurenai is saved by the arrival of her team, along with Naruto and Guy. Later, when explaining to Team 8 the reasons for her departure, she claims that the village "doesn't need any genjutsu users other than herself." This is her supposed reason for sealing Yakumo's abilities, but Shino recognizes that she was lying. Yakumo, on the other hand, believes Kurenai did so in order to eventually wipe out the Kurama clan. She traps her former sensei, Naruto, Sakura, and Team 8 in a genjutsu-created replica of the village which appears to have been ravaged by war. Unkai is also in the illusion. Concerned by the powers Yakumo has, and her continually degrading mental state as a result of being unable to control them, he frees Naruto from the illusion so he can kill Yakumo. Everyone else is freed, as well, except for Kurenai. Yakumo keeps her trapped in the illusion in the hopes of getting revenge and answers about her past. Naruto and the others head back to the mountain villa and Naruto re-enters Yakumo's genjutsu world to help Kurenai. Yakumo learns that a monster named Idou that lived within her subconscious mind was the one who killed her parents. With Kurenai's help, she overcomes the monster in her heart and frees Kurenai from her genjutsu. With her final mission from the Third completed, Kurenai re-assigns herself as the Jonin leader of Team 8.

Hidan and Kakuzu
As Asuma and his squad leaves to hunt for Hidan and Kakuzu, Kurenai looks on from her apartment, giving a curious yet uncertain gaze. She seems to notice something but when she looks to the window, the team has already left. While the battle is happening, she notices one of the flowers falls and senses something wrong with Asuma, and later she is seen gazing out at the rain with a fearful expression. When Asuma was killed, Kurenai broke down in tears when she learns of Asuma's death. She was the one who put flowers on Asuma's grave during the funeral. It is now revealed that she is pregnant with her's and Asuma's baby.

Abilities
As a natural genjutsuist, most of her techniques revolve around genjutsu. The one technique she is seen using the most, is the Demonic Illusion: Tree Bind Death technique. Kurenai can sneak up on an opponent and grow a tree around them to keep still. Once immobilized, Kurenai can appear from the tree to kill her target as she pleases, and is capable of using this jutsu multiple times in a row.

Trivia

 * "Yuhi" means "evening sun"
 * "Kurenai" means "crimson".
 * Kurenai's red lipstick is kinda a pun on her own name. The kanji for "Kurenai" can also be read as "beni" which is a word used for red makeup used traditionally in Japan to color the lips red.
 * Kurenai likes shochu, vodka, salted octopus, and taking a glass of wine at night or dinner. She dislikes cake.