Kurenai Yuhi
Kurenai Yuhi is the Konoha Jonin in charge of Team 8, which consists of Kiba Inuzuka, Shino Aburame and Hinata Hyuga.
Kurenai's 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.
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 somewhat aware of her student's tremendous infatuation with Naruto Uzumaki. When Hinata tries to offer Naruto some medicine after his fight with Kiba, Naruto is hesitant to take it (most likely because of the abuse he suffered in his childhood). Kurenai convinces him to take it. Her personality is unyielding, honest, and simple. She also says she is a "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 requests to tell her specially about Asuma's death (and Tsunade had offered to do so before), and she breaks down sobbing at the news. In the manga series the romantic relationship is proven by the fact that Kurenai wears a wedding ring on her left hand and is pregnant with Asuma's child.