Kakashi got his sharingan eye from a friend, a member of the Uchiha clan. Kakashi, Rin, Obito and Yondaime were on a mission, and Kakashi had become a jounin on his birthday so Yondaime made him mission leader and went off to help fight a part of some massive war. Then during the mission Rin got captured, but Kakashi did not want to go and get her (the reason for this is because his dad, the White Fang of Konoha, did the same thing and became a disgraced ninja and killed himself). Obito then went off to get Rin back since he has a similar attitude to that of Naruto, and as he fought the guy...