Rin Nohara

was a medical-nin and the teammate of Kakashi Hatake and Obito Uchiha under the Fourth Hokage in the Kakashi Gaiden exclusive.

Etymology
One possible meaning of her name means "cold". More likely, however, Rin is one of the readings of the kanji hayashi,. Usually when used for a woman's name it's written with the kanji for suzu,. Which meaning her name has is unknown, other characters from Konoha have names related to trees or leaves, but bells does have a relation, the bells used in the training by both Hiruzen Sarutobi and Kakashi in the series.

Kakashi Gaiden
She was a sweet and friendly woman who cared for her teammates and leaders. She shares many similarities to Sakura Haruno, such as the medical skills and similar hairstyle. She also had the same position in the love triangle of her team; Obito Uchiha had a crush on her, but she had a crush on Kakashi Hatake. Still, she was much more passive about it than Sakura; while Sakura repeatedly insulted Naruto, calling him stupid and such and almost always siding with Sasuke, Rin actually never called Obito any names or shouted at him, and when trying to break up arguments, she did not take sides. Her crush on Kakashi was not anywhere near as obvious as Sakura's crush on Sasuke, either; up until the time that Rin openly admits her feelings for Kakashi, the caring attitude she showed towards him could have been easily mistaken for teammate-like caring and concern.

When Rin was captured by enemy shinobi from Iwagakure, Obito and Kakashi went to go save her though it takes some prodding to get Kakashi to help.

Later, half of Obito's body is crushed by a rockslide in an attempt to save Kakashi. At Obito's request, Rin implanted Obito's remaining Sharingan eye into Kakashi's damaged left eye socket. After the cave collapsed on Obito, killing him, Kakashi told her that Obito had feelings for her, and she remained silent for a second before admitting her feelings for Kakashi. Kakashi told her that because he had deserted her, he was "nothing but scum" and then vows to protect her with his life, at Obito's request.

She is presumed dead, as Kakashi mentions he failed to protect her during his final thoughts before he seemingly died. Though there is chance she is alive, Kakashi may have meant that he failed to protect her because he's dying and was not able to keep his promise to Obito any longer. So assuming that's the point of view, she may very well be alive.

Abilities
As a medical ninja, Rin's primary duty in missions was to give support to her teammates. Despite her age, she was shown skilled enough to aid a team on a high-ranked mission. She also demonstrated high skill by quickly and successfully implanting Obito's remaining Sharingan eye into Kakashi with only basic medical tools.

Speculation
Some believe Rin might be a member of the Inuzuka clan because of the marks on her face resemble that which all of the Inuzuka members have. However, Rin's markings are a different color and shape to those of the Inuzuka Clan and she does not have any dog with her. Also some have stated that if she is indeed a member of the Inuzuka clan this could explain Kakashi's use of ninja hounds, as it could be a trait "garnered from friends" of sort. Also some think she is part of an unknown clan because in a flashback of Choji Akimichi one of the kids he was playing with had the same markings. Some also believe Rin may be related to either Naruto Uzumaki or Sakura Haruno. Another speculation is that Pain's new Animal Path is Rin, although this is highly unlikely.

Trivia

 * During Rin's first appearance in the anime (during a flashback in episode 72), Rin was shown to have dull brown hair, but during her next appearance (in a photo in the extra of Shippuden 64), she was shown with black hair.