Originally posted by: lasaire
I have a theory about Itachi. First, some background.

Tsukiyomi is the name of the attack Itachi uses on Kakashi and Sasuke to make them relive over and over horrible moments, which eventually causes mental damage and puts them in a coma-like state.

It's part of the 'mange sharingan' jutsu used by true sharingan successors.

Tsukiyomi appears to be a genjutsu which inflicts both mental and actual physical damage on the recipient: Kakashi collapses soon after being hit with it, and Sasuke falls almost immediately into a coma-state, with blood dripping from the corners of his mouth and his eyes eerily blank. (chapter 147)

Now, in the next chapter, 148, Kisame asks Itachi why he is retreating from Jiraiya. Itachi replies that there is no need to rush, that his body needs rest (implying that using the Tsukiyomi repeatedly takes a great deal of stamina/chakra) and also that:

"Not to mention, until Tsukiyomi becomes Amaterasu, we should not use it."

Now, the translation lists Tsukiyomi as 'moon' and Amaterasu as 'sun', thus "until the moon becomes the sun, we should not use it." However, Amaterasu is actually the sun goddess, the principal goddess in the pantheon of Japan's native religion, Shinto. The Imperial line was held to have descended from Amaterasu, hence why the Emperor is so revered.

What I think this means for Itachi: if Tsukiyomi is genjutsu so powerful that it causes both mental and physical damage and puts the user in a coma, and Amaterasu is a jutsu even more powerful, named after the highest goddess in Shinto myth, then Amaterasu must be a genjutsu that kills. What could be a more powerful jutsu than a way to kill someone only by locking their eyes with the sharingan?

No wonder Orochimaru wants Sasuke so badly.
Well, first off, it's Mangekyou Sharingan, not Mange. Mangekyou means kaleidescope, the use of "Mange" was a mistranslation or a lack of translation... it seems they forgot about the "kyou". Secondly, I wouldn't trust the translations as 100% accurate... chapters around that area were done by random people/groups. I have an English script from AK of Troy of Toriyama's World (the original group who translated Naruto) which has the conversation between Itachi & Kisame:

"Not to mention, until Tsukiyomi becomes Amaterasu, we should not use it."

As something entirely different. As for the translation of Amaterasu, from the kanji characters used, it can basically mean "Light of the Heavens". I'm not sure of the translation of Tsukuyomi, since there seems to be various ways to represent it in kanji... it can mean "Vision of the Night Moon", "Moon Reader", or "Moon Hell". As mentioned, Tsukuyomi is a genjutsu, but Amaterasu is most likely a ninjutsu considering the black flames which were created when Itachi closed his eyes and a big hole appeared in the wall.

If you've done your research about Shinto deities, you would know that there is a third, Susanoo, who is the "God of Storms", which could possibly represent Itachi's third attack... maybe a supreme taijutsu technique.

On a sidenote, if anyone happens the know the kanji used for Tsukuyomi in the Naruto manga could you post it here.