KakaRin

KakaRin is a Het ship between Kakashi Hatake and Rin Nohara in the Naruto series.

Canon
Kakashi and Rin were members of the same team along with Obito under Minato. Rin had a crush on Kakashi but he did not seem to noticed this or care. When Kakashi was promoted to Jonin, Rin gave him a medical kit as a gift to congratulate him on his promotion. They later went on a mission and Rin was captured by the enemy. Kakashi was more concerned about completing their mission but changed his mind after he was convinced by Obito.

Kakashi managed to save Rin from being tortured in a Genjutsu. However, Obito was fatally wounded so he had Rin transplant his Sharingan to Kakashi. As Obito was seemingly dying, he asked Kakashi to keep looking after Rin. In a later mission, Rin was captured and used to become a Jinchuriki bomb in hopes of destroying Konoha. She begged Kakashi to kill her but he refused. Because of this, Rin later jumped in front of Kakashi's Chidori and purposefully took a lethal blow in order to save the village. Kakashi teared him when she did this and decided that all of his friends were dead at this point.

Kakashi was upset over Rin's death and often went to visit her grave throughout the years. During the Fourth Shinobi World War, Kakashi encountered Obito on the battlefield and learned that he was still alive. Obito had witnessed Rin's death and was determined to create a world where he could see her again. Kakashi eventually convinced Obito to side against Madara and a vision of Rin grabbed both of their hands at one point.

Fanon
KakaRin is a rather popular pairing in the Naruto fandom and is one of the more popular ships involving Kakashi and especially Rin. It was mainly supported due to Rin's crush on Kakashi and some found that it paralleled SasuSaku. KakaRin became even more popular when the reason behind Rin's death was revealed as many found it to be sad and tragic. KakaRin rivals ObiRin as well as other pairings involving Kakashi.