Home Naruto Jutsus Tobi Sharingan

Name: Sharingan, 写輪眼, literally "Copy Wheel Eye", English anime dub "Mirror Wheel Eye"
Type: Kekkei Genkai
Users: Uchiha Sasuke, Uchiha Itachi, Hatake Kakashi and Tobi

The Sharingan is a special type of pupil that naturally occurs in all members of the Uchiha clan, though not all of them ever discover it. The Sharingan allegedly evolved from the Byakugan and grants the user a number of abilities. It is a dōjutsu (pupil technique). The Sharingan's first and most well known ability is to memorize any technique that it is a witness to. It can memorize ninjutsu (ninja techniques), genjutsu (illusionary techniques), and taijutsu (hand-to-hand techniques) with perfect accuracy and allow the user to use the techniques, as long as they have the necessary resources to do so. Second, it is capable of a unique brand of hypnosis that involves suggesting actions and thoughts to the opponent. Third, it can see through genjutsu, the level of which is possibly dependent on the user's skill. Fourth, it has the ability to predict (and copy) an opponent's movement as well as allowing sight of fast moving objects with great clarity.

The weakness of the Sharingan, in Kakashi's case, is that it drains chakra quickly. In order to copy a jutsu, one has to have the physical ability to perform the technique. For example, they have to have the needed amount of chakra, stamina, agility, and/or strength in order to perform said technique. In addition to physical skill, the Sharingan cannot copy any other bloodline abilities or summon a creature the user has not made a contract with because the user of the sharingan has to have the same blood of the other summoning user. In Itachi's and Sasuke's case, their chakra is still drained, but incredibly more slowly, due to the fact that they have the actual Kekkei genkai of the Uchiha clan.

The Sharingan does not automatically appear from birth in a user; instead, it will usually appear when the user is in a life threatening situation, where the power of the Sharingan will save the user. After this first appearance, the user can then call up the Sharingan any time he or she pleases. (Due to its unique nature, Kakashi's Sharingan seems to be "permanently on", and thus he covers it except during heated battles, to conserve chakra.) The power of the Sharingan is judged through the number of tomoe in the person's eye. It is not unheard of for a Sharingan user to have different amounts of tomoe in each eye. For example, Sasuke's Sharingan initially had two tomoe in one eye and one in the other. Eventually his Sharingan evolved to two tomoe in each eye, then three. An "adult" and fully matured Sharingan has three tomoe in each eye.

Interestingly enough, it is possible to transplant Sharingan eyes from one person to another, as is the case with Kakashi and his deceased comrade Obito. However, transplanted eyes do not work as well without an Uchiha body, causing much more strain on the user.