Shisui Uchiha was a shinobi from Konohagakure's Uchiha clan and was renowned as "Shisui of the Body Flicker" (Shunshin no Shisui).
Shisui was noted to be one of the most talented members of the Uchiha clan. At some point in the past, he fought with Ao of Kirigakure who retained an acute memory of Shisui's chakra colour, and the Uchiha's ability to control others with his Mangeky? Sharingan's ability.
Shortly after joining the ANBU, Itachi began to act "oddly", and Shisui was instructed by the Konoha Military Police Force to keep tabs on him. Soon afterwards Shisui was found drowned in the Naka River with a suicide note stating that he was tired of carrying out the clan's duties. The police suspected that Itachi had murdered him and used his Sharingan to fake the suicide note, since Shisui was very devoted to the clan, and suicide would have been highly unusual and uncharacteristic. Itachi later told Sasuke that he did kill Shisui and forged the suicide note, all in order to awaken his own Mangeky? Sharingan. Shisui's corpse has in fact disappeared, as even Kabuto Yakushi noted that he was unable to locate it.
However, Itachi would later reveal the truth behind the incident to his brother. Shisui was perplexed that the clan would not deter from the coup d'etat that they were planning and about the consequences that would follow their actions. He told Itachi that he had tried to use Kotoamatsukami to stop them, but Danz? Shimura stole his right eye, adamant on protecting the village his own way. Fearing that Danz? would get the other one as well, Shisui entrusted the other to Itachi telling him to protect the village and the Uchiha name. In order to prevent conflict from arising over his eyes within the clan, Shisui made it appear as though he had crushed them before dying. He would later erase his existence leaving no corpse behind.
