Clan Name: Uchiha
Kekei Genkai: The Sharingan's abilities consist of two parts: the "Eye of Insight" (洞察眼, Dōsatsugan) and the "Eye of Hypnotism" (催眠眼, Saimingan). The first of the Sharingan's powers is being able to see the flow of chakra. The Sharingan can tell if a person is under a genjutsu because the person's chakra flow would be irregular. The Sharingan's second-most prominent ability grants the user an incredible clarity of perception, allowing them to easily recognise genjutsu and different forms of chakra, though not to the same extent as the Byakugan. This also allows the user to pick up on subtle details, enabling them to read lip movements or mimic something like pencil movements.
As the Sharingan evolves, gaining more tomoe seals, this ability extends to being able to track fast-moving objects before finally giving some amount of predictive capabilities to the user, allowing them to see the image of an attacker’s next move from the slightest muscle tension in their body and counterattack or dodge without any wasted movement. However, even though the user may be able to see an attack or know it is coming, their body may not always have time to react.
The Sharingan's third and most well-known ability is that it grants the user the ability to memorise almost any technique that he or she witnesses, apart from other kekkei genkai techniques. The user can memorise ninjutsu, genjutsu, and taijutsu with near perfect accuracy, allowing the user to use the techniques as their own, or even modify them to create their own new techniques, much like Sasuke Uchiha's Lion Combo. In order to reproduce a copied technique, however, one must have the necessary skill or ability to perform them. A prime example is Rock Lee's brand of taijutsu. While Sasuke was able to copy some of Lee's moves, they put a much more significant strain on him since he hasn't trained nearly as much as Lee has. In addition to physical skill and kekkei genkai techniques, the Sharingan cannot reproduce techniques dependent on other factors, such as summons that the user has not signed a contract with.
The Sharingan's final commonly-used ability is capable of inducing a unique brand of hypnosis that involves suggesting actions and thoughts to the opponent through genjutsu cast by simple eye contact between both parties. More advanced Sharingan users can take the hypnosis ability even further to the point where a powerful summon like Manda or even the Nine-Tailed Fox may be controlled. When this was used against Manda and the Nine-Tailed Fox their eyes took on the tomoe pattern of the users' Sharingan while under hypnotic influence.
The hypnotic ability coupled with the other aspects of the Sharingan, can make the user appear as if they can "see the future". First, the user must perfectly mimic every move their opponent makes and possibly their thoughts and words through careful observation. Then, they suggest an action to the opponent such as hand seals for a technique that the opponent and Sharingan user already know and copy that. With these things done, the user can complete the action even before the opponent does, possibly using the Sharingan's genjutsu to confuse or delay them. As with other genjutsu, genjutsu cast by the Sharingan are capable of putting an opponent to sleep, inducing paralysis, replaying memories to someone else, or creating various illusions to deceive someone. The potency of the Sharingan's illusion is dependent on the user's knowledge and skill with implementing genjutsu.
In addition, more rarely used by the Uchiha clan, the Sharingan can allow the user to perform a unique type of genjutsu Izanagi. Using Izanagi, the user can warp reality for a short amount of time, changing reality into illusion and illusion into reality. Although to perform this technique, the user must have the DNA of both the Uchiha and Senju clan. However, this technique has been labelled a kinjutsu, because its use causes the eye that performed Izanagi to close forever.
Although the Sharingan consumes the user's chakra while active, the chakra levels that the user must exert is so insignificant that they can keep it active constantly. In fact, Itachi Uchiha was so masterful of it, he was able to keep it active for most of the time, only once deactivating it after using Tsukuyomi on Sasuke and Amaterasu to escape Jiraiya. However, when a Sharingan is transplanted to a non-Uchiha, the chakra drain is significant, leading them to cover it up when not in use, to stop the drain.
Clan Symbol: Clan History: The Uchiha clan descended from the elder of the two sons of the Sage of the Six Paths. The elder brother inherited the Sage's "eyes", powerful chakra and spiritual abilities. When it came time for the Sage to choose a successor, he questioned the two on what course of action they would follow to bring order to the world. The elder believed that might was the way to bring peace, while the younger believed love was the way. The Sage favoured the ideal of the younger brother, and therefore designated the younger as his successor, causing the elder to be filled with jealousy and hate. From this hate came what Tobi calls the Curse of Hatred (憎しみの呪い, Nikushimi no Noroi). From the younger son descended the Senju clan who would be the eternal rivals of the Uchiha.
Before the founding of the ninja villages, the Uchiha were one of the many mercenary clans for hire. Because of their Sharingan, the Uchiha clan came to be known as one of the two strongest clans, the other being the Senju clan. Madara Uchiha was particularly powerful, and, upon attaining the Mangekyō Sharingan, he took control of the clan. Under his leadership the Uchiha grew stronger, conquering whatever clans they came upon, such that, whenever the Uchiha clan was hired for a job, the opposing side would hire the Senju, and vice versa.