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. 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 Mangekyō 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 Mangekyō 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 Danzō Shimura stole his right eye, adamant on protecting the village his own way. Fearing that Danzō 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.

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 held 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 one of the most powerful genjutsu users of the clan. 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 apparently so unique and powerful, that Tobi wanted it for himself and was angry that Danzō managed to destroy it 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 after he influenced Itachi greatly as a friend, teaching him self-sacrifice and telling him that a true shinobi was one who protected the village from within its own shadow. This possibly influenced Itachi in his future actions and inevitably contributed to the staving off of a possible civil war within the village and a world war. Even years after his demise, Shisui's powers and actions marked the world. Both his Sharingan have been used by Danzō and Itachi to protect Konoha in their own ways. Both of his eyes have now been destroyed however; Danzō crushed his right eye at his last moments, and Itachi used Amaterasu to destroy his left eye after the genjutsu was used to free Itachi from Kabuto Yakushi's control. Itachi also stated that above all else, Shisui wanted someone to inherit his will, something that Itachi sees inside of Naruto. Part of Shisui's last request to his best friend included telling Itachi to protect the village. During the Fourth Shinobi World War, Itachi was able to do just that using Shisui's Mangekyō Sharingan ability: Kotoamatsukami to rewrite the control that his summoner had over him and fight on the side of the Allied Shinobi Forces. He was also able to confront the Impure World Reincarnation user and stop the technique altogether.

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."