In the series' universe, Kakashi is an elite ninja from the village of Konoha. As the leader of team 7, originally composed of Naruto Uzumaki, Sasuke Uchiwa, and Sakura Haruno, he is the first mentor of the main protagonists in history.
Kishimoto had planned to introduce Kakashi much earlier in the story, but eventually he delayed his entry to allow himself more time to work.
https://fr.wikipedia.org/wiki/Kakashi_Hatake
