@cjoker2, Thanks for repu too... kakashi didn't killed his close/bestfriend, but his close friends already dead on a mission(kakashi gaiden on manga chapter [b]239-244[/b]), shorten story obito(bestfriend) ask Rin to take out his left Sharingan eye to kakashi with her medical jutsu coz obito feel he already going to die..., after kakashi have a sharingan, he continue fight against their enemy n safe rin, but a few moment afterwards that obito dead. based on that chapter, kakashi have got Mangekyo Sharingan(MS) technique n developing that, that's why kakashi MS n itachi MS looks different. I don't know exatcly about Nagato, i know nagato on manga chapter [b]372[/b] when Jiraiya fight with Konan, There's Flashback about konan, nagato, n yahiko, where them come to Jiraiya, orochimaru, n Tsunade, to teach them ninjutsu, and after jiraiya teach them around 3 years jiraiya leave them n back to konoha...(only just that which I know about nagato). three great eye techniques is Rinnegan, Sharingan, Byakugan... *Sorry If My English Too Bad