|Kekkei Genkai|| Sharingan |
Shisui was a renowned member of the Uchiha clan. Little is known of his life except that he once fought Ao before, which was how Ao was able to recognize Shisui's distinguished sharingan on Danzō Shimura during the Meeting at the Five Kage Summit.
Some time after Itachi Uchiha entered ANBU he began acting strange and Shisui was assigned to keep an eye for him. Later, he was found dead drowned in a river with a suicide note. The elites thought Itachi had done this and used his sharingan to copy Shisui's handwriting to write the suicide note since during Shisui's lifetime he had showed great devotion to the clan. He is also known to be good friends with Itachi Uchiha even leaving him with the trust of his remaining sharingan after one was stolen by Danzo.
Kabuto mentions that he cannot find Sishui's body to resurrect him with Edo Tensei, which implies that Sishui must have eliminated his corpse somehow.
Shisui was deeply respected by Itachi. Itachi says that Shisui has taught him the lesson of self-sacrifice.
Shisui's sharingan was regarded as the best in casting genjutsus even Itachi admits that it was better than his own. With it, he can persuade a person's mind without the awareness of the one being controlled. Itachi claims that it would have been able to completely change Sasuke from having intentions of attacking the village to help protect it. Shisui's sharingan apparently was strong enough to override even Edo Tensei's control over the resurrected as seen when Itachi was released from Kabuto's control when he was resurrected.