Things that shouldn't exist: Mangekyo Sharingan

The Mangekyo Sharingan (万華鏡写輪眼, Mangekyō Sharingan; Literally meaning "Kaleidoscope Copy Wheel Eye") 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. The appearance differs from user to user; Kakashi's and Itachi's both resemble pinwheels, while Madara's and his brother's more look like more detailed forms of the basic three-tomoe Sharingan. Those who have the potential to obtain it must make a great sacrifice in order to obtain it – according to Itachi, they must kill their closest friend. Itachi, Madara, and his brother apparently do in fact do this to obtain the original version, but Kakashi has noted that everyone he cared about had died long before the start of the series, so how he developed his own variant is unknown. And apparently, the Mangekyo Sharingan can be transferred from person to person, as in the case with Sasuke. The major drawback of the Mangekyo Sharingan is that when it is first activated, it slowly begins to destroy the eyes until the user becomes completely blind. The only way to regain one's eyesight after losing it would be to steal the eyes of a sibling, combining the two Sharingan to create a new, more powerful, and immortal Mangekyo Sharingan which prevents blindness and might grant immortality.

In the long history of the Uchiha clan, only a few have been able to obtain the Mangekyo Sharingan-- Madara Uchiha being the first, and Izuna Uchiha being the second. At present, there are three people alive who can use the Mangekyo Sharingan: Kakashi, Madara, and Sasuke.

The Mangekyo Sharingan gives each user their own unique jutsu. Itachi's Mangekyo Sharingan enabled him to use Tsukuyomi, Amaterasu, and Susanoo. Kakashi's own version of the Mangekyo Sharingan allows him to use a space-time jutsu of his own in which he creates a localized dimensional warp, drawing everything in the immediate vicinity of the point into a singularity. Sasuke's hasn't displayed any unique abilities aside from Amaterasu, but it seems to utilize Genjutsu like Itachi's did.

Mangekyo Sharingan Variations

Itachi Uchiha

Itachi Uchiha gained the Mangekyo Sharingan by killing his best friend, Shisui Uchiha. With the Mangekyo Sharingan, Itachi is able to use the three most powerful jutsu of the Uchiha clan. The first is Tsukuyomi, a powerful genjutsu. This jutsu comes out of and puts strain on the left eye. Upon making eye contact with an opponent, Itachi can use Tsukuyomi to transport them to an illusionary world where days amount to a mere moment in reality. Because Itachi is in total control of this world, he can torture an opponent in any way imaginable, leaving them crippled and in a state of mental collapse, though he hasn't gone further than 3 days. The second jutsu is Amaterasu. This jutsu puts strain on the right eye, and caused his eye to bleed during his final fight with Sasuke. Described by Zetsu as the ultimate ninjutsu, it is shown to be capable of burning through almost anything by creating a jet-black flame said to be as hot as the sun and capable of burning for seven days and seven nights.

The final and most powerful of these jutsu is the devastating Susanoo Jutsu. The jutsu summons a massive ethereal warrior, which then fights on behalf of Itachi. In the left hand, the warrior wields Yata No Kagami (八咫鏡; Literally meaning "Yata's Mirror"), a shield that's capable of reflecting all attacks, and in its right, the legendary Totsuka no Tsurugi (十拳剣; Literally meaning "The Sword Ten Hands Long"), also known as the Sakenagi Longsword (酒刈太刀, Sakenagi Tachi; Literally meaning "Sake Cutter Longsword"). The Totsuka no Tsurugi, commonly sheathed in a sake jar held by a third hand growing from Susanoo's right forearm, is an ethereal weapon with an enchanted blade capable of sealing anything it pierces in an eternal dream-like illusion.

All of these jutsu, however, use massive amounts of chakra and also cause ever increasing damage to the user's eyesight, as the eyeball itself is engorged in blood and stressed enormously while being used; Itachi himself becomes exhausted if using them both consecutively and has to deactivate his Sharingan. Soon he claims that his ulterior motive is to steal Sasuke's eyes to awaken his own Eternal Mangekyo Sharingan. During the fight with Itachi and Sasuke, Zetsu has revealed that the "Left Mangekyo" possesses the Tsukuyomi and the "Right Mangekyo" holds Amaterasu. Interestingly, the right eye seems to bleed when Amaterasu is used. It is unknown where Susanoo comes from,and if Itachi even needs the Mangekyo Sharingan to make it work, although it is known that he needs to have at least awakened it to use it.

Although in Itachi's final fight the Mangekyo Sharingan techniques seemed to cause the respective eyes to bleed, this was never before seen to happen when the techniques were used. This may in some way be caused by Itachi's apparent weakness during this battle, or simply due to his usage of his Mangekyo over time.

Kakashi Hatake

Kakashi Hatake developed his own version of the Mangekyo Sharingan during the timeskip. Kakashi uses his to create a localized interdimensional space-time warp jutsu called Kamui, allowing him to target any 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 in a single day (compared to his other original move, Lightning Blade, which he can use four times a day).

The appearance of the pupil and tomoe in Kakashi's Mangekyo Sharingan differ from that of Itachi's; Kakashi's looks more like a pin-wheel. Before this was shown, it was thought that one had to kill their best friend to acquire the Mangekyo Sharingan, yet this has been dissproven in both Kakashi and Sasuke, as Sasuke did not kill Itachi persay, but rather the traumatic effect of loosing Itachi after discovering he was really trying to protect him caused his Mangekyo Sharingan to activate, while Kakashi states that everyone he cared for was already dead, and had been for years and he had not activated his Mangekyo Sharingan. Currently the cause of his Mangekyo's activation is unknown.

Madara Uchiha

Madara Uchiha was actually the first person to wield this dangerous weapon. When he was young, he and his younger brother were the first people to gain the Mangekyo Sharingan. He eventually grew blind from it, and he killed Izuna Uchiha and took his eyes, though Madara claims the eyes were a sacrifice from his brother for the good of the clan. This unlocked the "Eternal" Mangekyo Sharingan.

It is believed Madara used its power to control the Nine-Tailed Demon Fox and sent it to attack Konoha, though he denies this. Regardless, the attack failed because of the Fourth Hokage's sacrifice. The Eternal Mangekyo Sharingan in appearance looks identical to Madara's first Mangekyo combined with Izuna's Mangekyo.

The Eternal Mangekyo Sharingan also seemingly has more abilities and, according to Itachi, a fourth and final eye technique, which was the reason that was said by Itachi Uchiha why he spared his younger brother Sasuke - in the hope of taking Sasuke's eyes to achieve the Eternal Mangekyo Sharingan for himself.

Due to his claim that he will use the Tailed Beasts to return his eyes to their former glory, his Sharingan eyes have most likely been damaged, possibly by Hashirama Senju.

Izuna Uchiha

Izuna, Madara's brother, once possessed a Mangekyo as well, his took the appearance of three bars stretching out of his pupil. It is said that he developed his around the time Madara did.

Madara later pried these eyes out of his head (Madara claimed he gave them to him) thus creating Madara's Eternal Mangekyo, which took the appearance of Madara and Izuna's Mangekyo combined.

Sasuke Uchiha

After Sasuke's battle with Itachi, he wakes up in a cave with Madara nearby. Madara removes his mask to reveal his Sharingan, which upon sight triggers the activation of Sasuke's Mangekyo Sharingan (in the form of Itachi's) and the Amaterasu, setting Madara ablaze. However Sasuke seems to have no control of this and quickly clamps his hands over his eyes.

Madara then explains that Itachi properly transferred all of his eye techniques to Sasuke, to protect his little brother, as a fail safe. It should be noted that during the time Sasuke's Mangekyo Sharingan first emerged it was actually Itachi's dōjutsu transferred to him. This Mangekyo Sharingan still required someone close to him to die. Therefore, Itachi, knowing he had a terminal illness, pushed Sasuke to the limit in battle. This allowed Orochimaru to emerge so that Itachi could purge his influence from Sasuke. Then, by dying before his brother's eyes, he could become Sasuke's "sacrifice".

The first time Sasuke is shown with it is when he announces the formation of the new team "Hawk," to crush Konoha. Sasuke's Mangekyo Sharingan has shown the ability to use a genjutsu which can "exploit fearful hearts", in this case to extract information from a victim. This genjutsu could possibly be the Tsukuyomi. He can also use Amaterasu, this time against Kirābī, but with his own Mangekyo and with the opposite eye Itachi used it with. He can also put out the Amaterasu flames as seen with Kirābī and Karin when one of Kirābī's burning tentacles hit her.