Tsukuyomi


 * Name: Tsukuyomi, 月読, literally "Moon Reader"
 * Type: Kekkei genkai, No rank, Offensive, Short range (0-5m)
 * Users: Itachi Uchiha, Sasuke Uchiha (Presumably)

Named after the Shinto moon god, Tsukuyomi, this jutsu is the most powerful genjutsu in existence. It is unique to the Uchiha clan and only those with the Mangekyo Sharingan can perform it. When executed, the jutsu traps the target in an illusionary world that is completely controlled by the user. The user can do anything to threaten or stun the target. While it only takes a few seconds to complete in the real world, the user can make it seem as if days have passed for the target. Depending on the user's whim, they can either torture their target for days on end, or make them relive a traumatic event over and over. Once the jutsu is finished, the target will not be able to fight for some time, if they don't suffer complete mental collapse. An example of this is Kakashi Hatake, who had to be hospitalized for some time after Itachi preformed the Tsukuyomi on him.

While the illusion is never the same twice, some elements always remain. The first and foremost similarity is the red moon, which hangs in the sky of each illusion. The moon, in turn, casts a red light throughout the illusion, giving the background a blood-red appearance while the figures within the illusion are in a grayscale inverted color.

Because the Sharingan is the main factor in executing this jutsu, eye contact is required. When he used it on Sasuke Uchiha, however, Itachi seemed to force Sasuke to open his eyes. Sasuke had both eyes closed prior to Itachi's activation of the technique, but opened them in shock as Itachi used the technique. Alternatively, Itachi may have simply caused Sasuke enough pain to open his eyes, or Sasuke did so by himself, despite how unwise such an action was.

Such a powerful technique is not without its disadvantages, though. Because of the complexity of the illusion and the quickness with which it is executed, an enormous amount of chakra is necessary to perform it. To date, only Sasuke Uchiha was able to over come Tsukuyomi, turning the after effects back on Itachi.

Influence
Taking from the ancient Japanese myth of Amaterasu and Tsukuyomi where when Izanagi washed his face after escaping the underworld his right eye became Tsukuyomi the Moon God.