Uchiha Itachi is one of the main villains in the hit anime/manga series, Naruto. Currently a member of the Akatsuki organization, he seeks to unlock the true potential in his younger brother, Sasuke
Uchiha.
Itachi, being the prodigy of the Uchiha clan, killed all of the members of his clan, aside from his younger brother Sasuke. When asked why he destroyed his clan, he simply answered, "To gauge my strength", or something to that element. He tells his younger brother that the Mangekyo
Sharingan that he possesses is not merely a kekkai genkai, but it has a secret ultimate purpose that has yet to be revealed.
The Uchiha clan specializes in
Katon (fire) Jutsu techniques. The power of said techniques can be heightened with the use of the
Sharigan. The Uchiha clans kekkai genkai. (blood line limit) Another, more powerful form of
the Sharingan is the Mangekyo Sharingan, possessing the ability to cast
genjutsu instantly without flaw. One of the techniques that Itachi favors is Tsukyomi (Moon Reader). This genjutsu technique can submerge the victim into a limitless world that Itachi has complete control over. He can distort gravity, time, existence, and creation in this world. It's absolutely impossible to dispel.
Itachi told his younger brother Sasuke that, if he was to obtain the Mangekyo Sharingan, there would be three people capable of using it. This implies that Kakashi is capable of obtaining the Mangekyo Sharingan.