Sharingan

The is a dōjutsu kekkei genkai, which appears in some members of the Uchiha clan. It is one of the, along with the Byakugan and the Rinnegan. The Sharingan is also called, because of the many abilities it grants the user.

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Stages
The Sharingan is not automatically activated in the user by birth. It is only first unlocked under some stressful or emotional condition after which the Sharingan may be used freely. When the Sharingan is first activated by a user, it has a different number of around the central pupil, varying between users.

The wielder of the Sharingan, through continued use and training, changes its form further, which involves gaining more tomoe up to a maximum of three per eye. As the Sharingan develops, the user gains heightened abilities through the heightened ocular sense. For example, they can copy hand movements with one tomoe, predict a person's movement and copy techniques with two and fully use the Sharingan's abilities when it is fully matured.

Receiving the Sharingan
As already mentioned, the Sharingan needs to be activated by the user when they are faced with a difficult circumstance or placed under emotional stress. After its first appearance, the user can use the Sharingan any time he or she pleases. It is also possible to transplant Sharingan from one person to another, as occurred with Kakashi Hatake, who received his left eye's Sharingan from his dying comrade, Obito Uchiha. Because of this, Kakashi's Sharingan cannot be deactivated, and as using the Sharingan requires much more chakra from him than it does from an Uchiha clan member, he usually covers it with his headband to conserve chakra. Also, Kakashi needs to rest for a longer period of time after using his Sharingan extensively in battle. In a similar way, Danzō Shimura had a Sharingan instead of his normal right eye, that he gained from Shisui Uchiha, which he kept hidden under his bandages. Danzō also possessed ten Sharingan in his right arm, which is kept sealed until he needs them. It is also possible to transplant it to animals, as Itachi did with Shisui's Sharingan with one of his crows.

Mangekyō Sharingan


The Mangekyō Sharingan gives the user access to several powerful techniques, including the powerful fire technique Amaterasu, the use of Susanoo and the almost unbreakable genjutsu Tsukuyomi. The Mangekyō Sharingan however erodes the eyesight of its users, eventually causing blindness, which can be prevented by obtaining another pair of Mangekyō Sharingan from a sibling. The new Sharingan is dubbed the.

Beyond Eternal Mangekyō Sharingan
After the Eternal Mangekyō Sharingan is achieved, the next step in the evolution of this dōjutsu is the Rinnegan. This fact was written on the Stone Monument of the Uchiha. Madara was able to awaken the Rinnegan shortly before his death through unknown means.

Trivia

 * Some characters believe that the Sharingan was somehow derived from the Hyūga clan's Byakugan. It is however revealed by Tobi that the Sharingan is evolved from the Uchiha Clan Ancestor's dōjutsu, which is evolved from the Rinnegan. It is unknown where or even if the Byakugan fits into this lineage.
 * In the anime, two of Sasori's hundred puppets are seen with what appears to be Sharingan eyes.