Mangekyō Sharingan

The is a heightened form of Sharingan. The Mangekyo Sharingan is distinguished from a normal Sharingan through its appearance, which changes the form of the tomoe seal. Unlike in the case of the Sharingan, the appearance of the Mangekyo Sharingan differs from user to user; Kakashi Hatake's and Itachi Uchiha's both resemble pinwheels, Madara Uchiha's and his brother, Izuna's look more like a detailed form of the basic three-tomoe Sharingan, and Sasuke Uchiha's looks like a star. To acquire the Mangekyo Sharingan, someone close to a Sharingan user must die and the emotion of the loss is responsible for its unlocking. To expedite this occurrence, most Uchiha throughout history have killed their closest friends or family members in order to meet this criteria. Although, how Kakashi gained his Mangekyo Sharingan has yet to be explained.

The Mangekyo Sharingan gives the user access to powerful and forbidden techniques. It is unclear if these techniques are unique among individuals; only two Mangekyo Sharingan users have been seen using the same jutsu, but Madara appears knowledgeable of all Mangekyo Sharingan techniques. The only known exception to this is Amaterasu, which Itachi implants in Sasuke's eyes before dying.

Over time, use of the Mangekyo Sharingan deteriorates the user's eyesight to the point of blindness. Only by taking and transplanting the eyes of one's sibling (who also wields the Mangekyo Sharingan) can the vision be restored, a process that results in the creation of the. Not only does this process restore one's eyesight, but it also gives the person greater power. It also gives a new eye technique. There are only three living shinobi left who possess the Mangekyo Sharingan: Kakashi Hatake, Madara Uchiha, and Sasuke Uchiha.

Itachi Uchiha
Itachi Uchiha gains the Mangekyo Sharingan by killing his best friend, Shisui. With the Mangekyo Sharingan, Itachi is able to use at least three (and the most, as of yet) of the most powerful jutsu. The first is Tsukuyomi, an extremely powerful genjutsu that allows him to torture opponents for what seems like days in a matter of moments. The second technique is Amaterasu, a substantially potent ninjutsu, which creates virtually-inextinguishable black flames at the user's focal point that continue to burn until the target is reduced to ash. The last of these techniques is Susanoo, which allows Itachi to summon a massive ethereal warrior. This entity fights on behalf of Itachi and shields him from all attacks, rendering Itachi essentially invincible.

All of these techniques use massive amounts of Itachi's chakra and, in addition to damaging his eyesight, put a great deal of strain in his body. During his final battle against Sasuke, Itachi's eyes are even shown bleeding after using the Mangekyo. He also tells his brother that he wants to take his eyes so that he can restore his eyesight and gain more power. During the resulting battle, Zetsu notes that Itachi's "Left Mangekyo" possesses the Tsukuyomi, while the "Right Mangekyo" possesses the Amaterasu.

Kakashi Hatake
Kakashi Hatake develops his own version of the Mangekyo Sharingan during the time-skip. With his Mangekyo Sharingan, Kakashi masters a technique that creates a localized inter-dimensional space-time ninjutsu called Kamui, allowing him to target any person and/or object and send it to another dimension. The attack requires considerable effort to aim precisely and appears to leave Kakashi's chakra significantly drained; He collapses after using the technique three times even at full strength in a single day. How he awakens his Mangekyo Sharingan remains unknown, as he states that everyone close to him was dead.

Madara Uchiha
Madara Uchiha is the first Uchiha to gain the Mangekyo Sharingan. His Mangekyo took the form of a ring with three circular holes in it. He eventually grew blind from overusing it, and only by taking his younger brother Izuna's eyes did he regain his sight. This also gave him an "Eternal" Mangekyo Sharingan that gave him great power. His Eternal Mangekyo Sharingan looks identical in appearance to Madara's first Mangekyo combined with Izuna's Mangekyo.

Madara, currently posing as Tobi, has shown using an unnamed space/time ninjutsu which makes him nearly invulnerable and allows him to teleport to different places at will very quickly, but it's unclear if this is a result of his Mangekyo Sharingan. He can also put out the so-called inextinguishable flames of Amaterasu quite easily.

In the past, Madara was able to use his Mangekyo Sharingan to control the Nine-Tailed Demon Fox like a pet. He has since claimed that gathering the nine tailed beasts will return his eyes to their former glory, suggesting his Sharingan have become damaged.

Izuna Uchiha
Izuna Uchiha acquires his Mangekyo Sharingan soon after Madara did. His took the appearance of three bars stretching out of his pupil. Madara later took Izuna's eyes to regain his lost vision. In Madara's story, however, Izuna volunteered to give him his eyes for the clan's sake.

Sasuke Uchiha
Sasuke Uchiha awakens his Mangekyo Sharingan after the death of his older brother, Itachi. Sasuke's Mangekyo takes the appearance of a six-sided star often resembling the atomic model. Unlike other Sharingan, which have a black design and red background, Sasuke's Mangekyo is the first one that is shown to have a red design and a black background.

The only unique ability that Sasuke has displayed using the Mangekyo is Amaterasu, which Itachi implanted within his eyes before his death. When Sasuke first uses it unintentionally against Madara, his eyes take the appearance of Itachi's Mangekyo Sharingan. When he later uses it on his own against the Eight-Tailed Giant Ox, it takes the form of his own Mangekyo Sharingan. He suffers from the same drawbacks from using it as Itachi did, as his eye strained to the point of bleeding, as well as his eyesight gradually began to deteriorate. Sasuke has also been seen using genjutsu with his Mangekyo Sharingan, though it has yet to be named.

Trivia
It seems that Itachi is the only Mangekyo Sharingan user to have three different Mangekyo forms.