Genjutsu is much less of a jutsu and more of a classification of Jutsu. While Taijutsu and Ninjutsu do not rely entirely on chakra, Genjutsu can not be performed without it.
Genjutsu is not real – it causes illusions which the victims think are real, which makes them stunned in one place. While the occurrences in Genjutsu aren’t always real, it can be a powerful tool which can destroy a person mentally.
Genjutsu has been something that has been around since the first Ninjas. The Sharingan and Byakugan, the two abilities Hamura and Hagoromo Otsutsuki possessed, are known for their potency in Genjutsu which makes it as old as Ninjas themselves.
The Uchiha are especially known for their skills in Genjutsu to such an extent that they can perform Genjutsu that instead of creating illusions can change reality itself. This technique is known as Inazagi. The Uchiha can also create alternate realities which exist in a different plane and time in their head. For example, Itachi Uchiha tortured Kakashi Hatake for 3 days inside his Tsukuyomi while it took only a few seconds in the real world.
While most can learn Genjutsu with practice, not everyone can master it. Genjutsu can be countered either very easily or could be almost impossible to break free from depending on how strong the caster is. These are some of the most powerful Genjutsu users:
Itachi is known for his Genjutsu and he is seen trapping any enemy that attacks him in a Genjutsu. While they think they are winning, they snap back to reality and realise they have been put in a genjutsu all along.
It is so powerful that he could trap Kakashi Hatake and Sasuke Uchiha, who are also Sharingan wielders, in a Genjutsu. The Sharingan resisted Genjutsu and yet they were trapped in one. He also traps Kabuto in an infinite Genjutsu known as Izanami.
Sasuke is especially powerful since he can use Genjutsu with the Rinnegan. Even Madara Uchiha had to convert his Rinnegan back into a Sharingan to use it. This shows the extent to how strong Sasuke’s Sharingan and Rinnegan really are.
While Madara doesn’t use Genjutsu much during a fight, his Genjutsu is possibly one of the strongest. He was strong enough to cast the Infinite Tsukuyomi, the ultimate Genjutsu which would give everyone a life they desired.
Although she was mocked by the community for trying to cast a Genjutsu on an Uchiha, her title of the strongest Genjutsu user in Konoha, during early Naruto days, speaks for itself.
Kaguya is one of the strongest Genjutsu users without a doubt. Naruto and Sasuke only won the battle due to Sasuke’s Rinnegan which could repel it. Without a Rinnegan, anyone is helpless against Kaguya as such is the potency of her Genjutsu.
Itachi uses Inazami on Kabuto, putting him in a loop which would cause him to break down.
Danzo is one of the most hated characters in Naruto. As gross as it is, him putting the Sharingans to use while fighting against Sasuke Uchiha was incredible, even though he wasn’t an Uchiha.
One of the most iconic moments in the Sasuke vs Itachi fight. Sasuke defeats Itachi, but only for him to find out that it was just a Genjutsu all along.
Itachi traps Kakashi Hatake in a Genjutsu for 72 hours; but there’s a catch – it only takes a single second in real time. The power of Itachi’s Tsukoyomi is at display here
One of the first instances of Genjutsu seen in the anime. Kakashi uses Genjutsu to show her a very injured Sasuke and causes her to fail.
A. You can release yourself from a Genjutsu by disrupting the flow of Chakra from your body. This temporary block will reset your system and will let you see through the Genjutsu. It can also be released by a teammate.
A. While Itachi is not immune to Genjutsu, his visual prowess could allow him to see through it. However, if a Genjutsu more powerful than what his eyes could capture were to be cast on him, he would not be immune to the effects of it.
A. Genjutsu is hardly used due to its extremely difficult nature. While people who possess the Sharingan or the Byakugan have a much easier time in terms of learning Genjutsu, that is not the case for the others, hence it being rarely used.