There seem to be some confusion as to what exactly Tuskuyomi is in regards to Genjutsu. Lets break this down
1st, What is Genjutsu? Genjutsu are techniques that are employed in the same fashion as ninjutsu, However, the primary difference between the two is that the effects of genjutsu are illusory; instead of attacking the victim's body, like taijutsu or ninjutsu, genjutsu techniques manipulate the flow of chakra in the victim's brain, thus causing a disruption in their senses.
2nd, How is a Genjutsu deployed? Genjutsu is created when a ninja extends their chakra flow through the cerebral nervous system of their opponent to control their mind, thereby affecting their five senses. Genjutsu attacks usually require a lot of skill, and, if performed incorrectly, will not work. Because genjutsu affects activity throughout the prosencephalon structure of the brain, humans, dogs and other species of mammal are therefore all affected by genjutsu.
3rd, How does one break Genjutsu? The ninja need first become aware that they are under Genjutsu. The ninja then needs to stop the flow of chakra in their body, and then apply an even stronger power to disrupt the flow of the caster's chakra; this is called Genjutsu Dissipation. This can also be done by an unaffected ninja by applying a sudden surge of chakra into the affected person. Another is through intense pain not caused by the genjutsu and utilising the resulting pain to bring their senses back in order.
Now these are the 3 main points for Genjutsu, now lets move to Tuskuyomi
1, what is Tuskuyomi? Tsukuyomi is one of the most powerful genjutsu in existence. It is unique to the Uchiha clan and only those with the Mangekyō Sharingan can perform it.
2, how does it work? Tsukuyomi requires eye contact to be performed, trapping the target within an illusion completely under the user's control.
A: Itachi's prowess with it: Itachi's prowess with the technique has allowed him to alter the perception of time with ease within the genjutsu to make a few seconds seem like many days as a means to torture the target. This results in the victim suffering psychological trauma that incapacitates them for a considerable period of time.
B: sasukes prowess: Sasuke can also perform Tsukuyomi with his right eye, though his illusion is considered inferior to Itachi's Tsukuyomi since it does not alter the opponent's perception of time indicating he has yet to master it.
3, how does one break it? Itachi states that Tsukuyomi can only be broken by a Sharingan user that shares the same blood as the caster; as demonstrated when Sasuke overcame Itachi's Tsukuyomi in their battle.
4, what are the drawbacks? Such a powerful technique is not without its disadvantages however. Due to the complexity of the illusion and the quickness with which it is executed, an enormous amount of chakra is necessary and an added amount of stress is placed on the left eye, leaving Itachi's vision more blurred.
As we can see that while Tsukuyomi is a Genjutsu, it differs greatly from any other of its type. The amount of chakra needed, the speed at which is need be used and the duration at which it last combined with the victims preception of that same duration, place Tsukuyomi in it own class of Genjutsu.
Only Tsunade has been shown capable of curing this psychological damage. Key word is '"CURE". I can fully imagine she can fixed the damage it can cause, however, that is not even close to being able to "break" it, the two are very different!
As I have stated above, in order to break Genjutsu, the user needs to beaware they are trapped in one. Tsukuyomi is instant so it counters the very 1st step in breaking Genjutsu. Also the ninja needs to share blood type, this is straight from Kisi mouth. I understand people wanna be fanboy and fangirls, but Im sorry, she cant breakt it!
