Kurenai Yūhi

is the Konoha Jōnin in charge of Team 8, which consists of Kiba Inuzuka, Shino Aburame, and Hinata Hyūga. Kurenai's team specializes in tracking, and she, herself, is an expert in genjutsu.

Background
Relatively little is known about her, other than the fact that she graduated from the Academy at the age of 9, took the Chūnin Exam and became a Chūnin at the age of 13, and that she only became a Jōnin a little while before the start of the series.

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. Because of this, the Third Hokage tasked Kurenai with helping to train Yakumo Kurama, another talented Genjutsu user who longed to be a ninja. However, because Yakumo couldn't control her illusions and thus endangered those around her, Kurenai had to seal away her ninja abilities, in turn keeping her from ever becoming a Shinobi.

Personality
While she has a close bond with all of her students, she is especially concerned for Hinata. Kurenai knows how Hinata is viewed by her father, even though she is technically the heiress of the clan since she is the eldest child. She is also aware of her student's infatuation for Naruto Uzumaki. When Hinata tried to offer Naruto some medicine after his fight with Kiba, Naruto was hesitant to take it. Kurenai convinced him to take it. Her personality is unyielding, honest, and simple. She also says she is a "big sister type".

It has been heavily hinted that Kurenai was romantically involved with fellow Jōnin Asuma Sarutobi. The two appeared together in most of their scenes, and the other characters made it a point to note this fact on several occasions. When Kakashi Hatake found the two together at a dumpling shop, he asked if they were on a date, which made Kurenai blush. During Asuma's battle with Akatsuki members, Hidan and Kakuzu, Kurenai was often shown wondering about his progress, appearing anxious. When she learned of his death, she fell to her knees in disbelief, and later laid flowers on his grave during his funeral. The truth of their relationship was made clear in Part II when Kurenai revealed that she is pregnant with Asuma's child.

Chūnin Exam arc
During the Chūnin Exam, Kurenai watched her pupils from the sidelines. After Shino's battle, she commented on how it suddenly became cold in the room, in reference to his rather merciless defeat of Zaku Abumi. During Kiba's fight with Naruto, she thought to herself (and commented to Kakashi) that Naruto couldn't possibly beat Kiba, only to be surprised again and again as Naruto took everything Kiba threw at him. During Hinata's fight with her cousin, Neji Hyūga, she remembered the terrible relationship Hinata had with her father. She also noted the stark contrast between the current Hinata, who refused to give up, and the former Hinata, who would give up easily. When Neji was sent into a blind rage and tried to kill Hinata, Kurenai helped stop him along with every other Konoha Jōnin present, except for Asuma.

She was seen again during the third round matches and the invasion of Konoha, as well as the Third Hokage's funeral.

Return of Itachi arc
Soon after Konoha proved successful in defending the village, Kurenai and Asuma discovered that the Akatsuki members, Itachi Uchiha and Kisame Hoshigaki, had infiltrated the village. The two pairs engaged each other in battle, but Itachi proved to be easily capable of turning Kurenai's Genjutsu against her. Before she and Asuma could be finished off, Kakashi arrived to save them, only to be caught in Itachi's Tsukuyomi, and was then saved by Might Guy.

Kurama Clan arc
This was a filler arc.Yakumo resurfaced several years after Kurenai had sealed away her kekkei genkai, which ultimately proved unsuccessful. After Yakumo created the illusion of the Hokage Residence being struck by lightning (something everyone believed to have actually happened), Kurenai took a temporary leave from Team 8 so that she could deal with the problem. Naruto confronted her about her involvement with Yakumo, but she simply used a genjutsu on him to keep him occupied.

As she approached Yakumo's cabin, Kurenai appeared to be trapped in a rebel's genjutsu. In actuality, she had attacked her attacker in a genjutsu. She discovered that these attackers were in fact Kurama clan members, who were intent on kidnapping Yakumo. From this point, she and the opposing ninja basically fought with nothing but Demonic Illusion: Tree Bind Death, using variations on the standard theme of the jutsu. Kurenai ended up successful until the final encounter, where she was caught off guard and cut by shuriken. The blood revealed her presence to Unkai, the temporary leader of the Kurama clan, allowing him to defeat her.

Kurenai was saved by the arrival of her team, along with Naruto, Sakura, and Might Guy. Later, when explaining to Team 8 the reasons for her departure, she claimed that the village "doesn't need any genjutsu users other than herself". This was her supposed reason for sealing Yakumo's abilities, but Shino recognized that she was lying. Yakumo, on the other hand, believed Kurenai did so in order to eventually wipe out the Kurama clan. She trapped her former sensei, Naruto, Sakura, and Team 8 in a genjutsu-created replica of the village which appeared to have been ravaged by war. Unkai was also in the illusion. Unkai, concerned by the powers Yakumo had, and her continually degrading mental state as a result of being unable to control them, freed Naruto from the illusion so that he could kill Yakumo. Everyone else was freed as well, except for Kurenai. Yakumo kept her trapped in the illusion in the hopes of getting revenge and answers about her past.

Naruto and the others headed back to the mountain villa and Naruto re-entered Yakumo's genjutsu world to help Kurenai. Yakumo learned that a monster named Ido that lived within her subconscious mind was the one who killed her parents. With Kurenai's help, she overcame the monster in her heart and freed Kurenai from her genjutsu. With her final mission from the Third Hokage completed, Kurenai reassigned herself as the Jōnin leader of Team 8.

Part II
Kurenai appears regularly during and following Asuma's battle with Akatsuki. When told of Asuma's death, Kurenai was devastated. After Shikamaru avenged Asuma's death by defeating Hidan, he started taking care of Kurenai for Asuma's sake (although she has been known to insist he does not need to do so every day). He also vowed to someday make the child his student. Because of her pregnancy, Team 8 has been led by other Jōnin during its missions.

Hidan and Kakuzu arc
At the hospital, Asuma wanted to tell Kakashi something. But he can say anything, Kurenai enters and Asuma takes his leave, stating he'll tell Kakashi later. Later, as Asuma and his team go off to track down Hidan and Kakuzu, he looks on at an apartment window and tells his team to move out. Inside, its revealed that its Kurenai's apartment. She senses something, but when she turns to look out the window, Asuma and his team are gone. As Kurenai is watering flowers that were given to her by Asuma, one of the petals falls off its stem, and she is hit with an ill omen about Asuma. As Shikamaru return, he tells her the grim news of Asuma. Kurenai stares on in shock and then collapses to her knees devastated, and during Asuma's funeral, Kurenai is holding flowers. After Shikamaru avenges Asuma's death by defeating Hidan, she finds him at Asuma's grave. She asks him if he'll be lonely now that his Shogi partner is gone. Shikamaru states Asuma taught him both important and stupid stuff. He reflects that he brushed off responsibility and whined when he was young, and Asuma would have to protected him. He was the coolest adult he knew, and he tells Kurenai, when she has her baby, he'll help protect it as a cool adult too. Kurenai holds her stomach and smiles.

Invasion of Pain arc
To help Naruto get over Jiraiya's death, Shikamaru takes him to the hospital where Kurenai is leaving and he explains to Naruto that she's pregnant. Kurenai insist to Shikamaru that he does not need to check on her every time she goes to the hospital, but Shikamaru says he can't help it, Asuma told him to watch over her and the child.

Abilities
As the top Genjutsu specialist of the Leaf Village, most of her techniques revolve around Genjutsu. Her skill at Genjutsu is so great that it is able to enter the subconscious of a person to see one's true nature. The technique she is seen using the most is the Demonic Illusion: Tree Binding Death technique, where she makes the opponent believe that a tree has grown around them to keep them 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. She is also capable of escaping and engulfing her opponents in illusionary flower petals as well, thus proving most of her genjutsu involve flora and fauna objects.

Trivia

 * "Yūhi" means "evening sun".
 * "Kurenai" means "crimson".
 * Kurenai's red lipstick is, in a way, a pun on her own name. The kanji for "Kurenai" can also be read as "beni", which is a word used for red make-up used traditionally in Japan to color the lips red.
 * After Kurenai was revealed to be pregnant, she is seen with a ring on her finger. It is unclear if this is a wedding ring, an engagement ring, or something else.
 * During a question and answer session held at Tokyo's Jump Festa '09, Masashi Kishimoto stated that he was thinking of making Kurenai and Asuma's child a girl.
 * Although her eyes are very distinct, they are not a Dōjutsu.
 * Kurenai is the only one of the four principal sensei (Asuma, Kakashi, Guy, and herself) who doesn't regularly wear a flak jacket; the only two times she is seen wearing one was in a flashback with Hiashi Hyūga and in a scene with her and Asuma. She can also be seen wearing it in Naruto Shippūden: Ultimate Ninja 5 and Naruto Shippūden: Narutimate Accel 3.
 * Kurenai is a playable character in Naruto: Clash of Ninja Revolution 2, Naruto Shippūden: Clash of Ninja Revolution 3, Naruto: Ultimate Ninja 3, Naruto Shippūden: Ultimate Ninja 4, Naruto Shippūden: Ultimate Ninja 5 and Naruto Shippūden: Narutimate Accel 3.
 * According to the databook:
 * Her hobby is drinking evening drinks.