Shisui Uchiha

was a shinobi from Konohagakure's Uchiha clan and was renowned as.

Background
Shisui was noted to be one of the most talented members of the Uchiha clan as well as the most powerful genjutsu user of the clan. At some point in the past, he fought with Ao of Kirigakure who retained an acute memory of Shisui's chakra colour, as well as the Uchiha's ability to control others with his Mangekyō Sharingan's ability.

Shisui was best friends with Itachi Uchiha, who shortly after joining the ANBU began to act "oddly". Shisui was instructed by the Konoha Military Police Force to monitor Itachi because of this. 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 of him. Itachi later told Sasuke Uchiha that he did in fact kill Shisui and forge the suicide note, all in order to awaken his own Mangekyō Sharingan.

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 Shisui was greatly concerned with the consequences that would follow their actions. He told Itachi that he had tried to use Kotoamatsukami to stop them, but Danzō Shimura stole his right eye, adamant on protecting the village his own way. Fearing that Danzō would get his left eye as well, Shisui entrusted it to Itachi, telling him to protect both 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. It would appear that Shisui's corpse had in fact disappeared, as even Kabuto Yakushi noted that he was unable to locate it. Shisui was one of Kabuto's prime candidates to be reincarnated.

Personality
Itachi was Shisui's best friend; in fact, Itachi thought of him as a brother. Shisui taught Itachi that "self-sacrifice… a nameless shinobi who protects peace from within its shadow…" was the true mark of a shinobi. Shisui was also very devoted to the clan, which is why the Konoha Military Police Force asked him to spy on Itachi. It is because of this devotion that the police did not believe he could have committed suicide.

Along with his clan, Shisui was greatly devoted to the protection of the village which he cared for deeply. He even went as far as to attempt to put his clan under a genjutsu in order to stop their coup d'etat which would lead to civil war. With this in mind, he entrusted his left eye to Itachi and told him to protect the village. According to Itachi, he and Naruto Uzumaki hold similar ideals and goals.

Appearance
Shisui had short, unkempt, dark-coloured hair and a relatively broad nose and well-defined eyelashes, that were turned upwards at each end. In the anime however, these lines are broken instead of whole. He wore the standard attire of the Uchiha clan which includes a high-collared, dark-coloured outfit along with a tantō strapped to the right side of the back of his shoulder. He also wore what appeared to be a harness for his tantō which ran across his chest and fastened over both his shoulders.

Abilities
Shisui was noted to be one of the most talented members of his battle-excelling clan. He had earned the nickname of "Shisui of the Body Flicker", possibly implying that he had great mastery of the Body Flicker Technique. He was also hailed as the most powerful genjutsu user of the clan according to Killer B. Another testament to his prowess is that Kabuto Yakushi wanted to reincarnate him for the war but failed to find sufficient DNA samples. He also displayed a high level of pain tolerance, as he didn't flinch from ripping out his own left eye to give to Itachi.

Sharingan
Like many members of his clan, Shisui was a wielder of the Sharingan. Alongside his friend Itachi, he was praised for his mastery and sheer power in its use.

Mangekyō Sharingan
Shisui was one of the few members in the clan's history that was able to awaken the Mangekyō Sharingan. It granted him access to powerful genjutsu techniques, the strongest of which was a unique genjutsu noted to be of the highest calibre: Kotoamatsukami. This technique allowed him to enter a person's mind and manipulate them by giving them false experiences, making it seem as if they were doing things on their own free will; the victim wouldn't even notice they were being manipulated.

This ability was so unique and powerful, that Tobi wanted it for himself and was angry that Danzō managed to destroy the eye before he died. Kabuto was also extremely thrilled when he learned that the remaining eye was within Itachi's crow. This genjutsu however, could only be used once a decade, unless the user had a way to augment the process such as with Hashirama Senju's cells, thereby drastically reducing the time required from ten years to only a few hours. Shisui's eyes were also seen as something of a treasure even within his own clan, as before his death he had to ensure that it looked like he had destroyed them before he had died, fearing it would end in conflict otherwise.

Legacy
Throughout his lifetime and even in death, Shisui influenced Itachi greatly as a friend in teaching him self-sacrifice and how a true shinobi must protect his village from within its own shadow. This possibly influenced Itachi in his future actions to the staving off of a possible civil war within the village that may have escalated into a world war. Even years after his demise, Shisui's powers and actions left their mark on the world. While Danzō used the eye he stole for his questionable agendas to maintain their village, Itachi keeps Shisui's other eye to honour his friend's final request to protect the village and their clan's good name. Inserting the eye in the body of a crow, Itachi made final arrangements to implant the bird in Naruto's body as a counter measure against Sasuke if he learned the truth behind the Uchiha Clan's demise and attempted to destroy Konoha.

Both of Shisui's eyes were eventually destroyed: Danzō destroying his eye in his final moments to keep it from Obito Uchiha's grasp and a reincarnated Itachi, after it was accidently used on him, incinerating the crow so that the left eye would not fall into enemy hands. But Itachi also stated that above all else, Shisui wanted someone to inherit his will and ideals, believing Naruto to be that someone.

Trivia

 * Shisui's name has two interpretable meanings. Combining the words and, Shisui would mean "death water", which is a reference to his death by drowning.  alone means "still water" or "stagnant water".

Quotes

 * (To Itachi) "…You're my best friend and the only one I can count on… Protect the village… and the Uchiha name."