Kotoamatsukami
Yugito was silently listening to Itachi and Shisui discuss about a justu she has never heard of.
This jutsu apparently changes the mind of anyone it was used on, if that was true this was a forbidden technique and a scary one too.
"Does something like that really exist? Can all Sharingan do that?"
Yugito asked Shisui, who shook his head.
"It does exist but not every Uchiha can do it."
"Sharingan has a stronger form, the Mangekyo Sharingan, every Mangekyo Sharingan has it's own justu, mine is Kotoamatsukami, the ability to change the will of others."
It would be a lie to say that Yugito wasn't concerned, she just heard someone say they can change anyone's will, so was her will also changed without her knowing?
That was a scary thought.
'She's afraid of me.'
Shisui who owned this jutsu knew the look on Yugito's face very well, it was the look of someone doubting him.
He knew he should quickly explain his justu if he wanted to be trusted and not feared.
"Don't worry, only my left eye can change someone's will permanently, it's genjutsu cannot be broken, and it has a ten year cooldown after each use."
"My right eye dosen't have a long cooldown, it's just a few hours, but it's genjutsu can be broken."
"Although it's only possible if the person knows that they are in a genjutsu, normally the genjutsu of my right eye is impossible to detect unless someone uses a Byakugan when I am casting it."
Shisui told the positives and negatives of his technique clearly, this should give Yugito peace of mind.
But Shisui was still a Ninja, he didn't tell all his information out of instinctive caution.
He didn't tell her that eye contact was needed for his left eye to work, or that his right dosen't need any eye contact.
In fact his right eye dosen't need to see the person completely either, even if his eyes was bandaged and he couldn't see a thing, he could still activate his right eye anyway.
As long as he had a vague idea where someone's chakra was, he was good to go.
'He didn't tell her everything eeh, no harm done, I'll tell her about it later.'
Sato meanwhile was looking at them with a smile on his face, he knew everything about Shisui's justu, so he didn't fear it at all.
Not because Kotoamatsukami wasn't strong, but because it's user Shisui was filled with positivity and was a nice guy.
Shisui would never use this overpowered ability on someone without a really, really good reason.
If he was even a little bit smarter with Kotoamatsukami, he would have saved the Uchiha by himself now.
"I see, your permanent mind changing justu has a ten year cooldown."
"Use that one on Itachi then, I can rest assured that he won't break out of the justu if it's permanent."
Yugito tapped the ground like Sato does and told them what to do.
But she didn't tell them the real reason, she wanted Shisui to use this jutsu on Itachi so it's cooldown can start, she won't have anything to fear about it then.
She was basically a perfect jinchuriki, she didn't fear genjutsu which can be broken, and his right eye's genjutsu could be broken, unlike his left eye's.
"We will do that."
Shisui and Itachi both agreed, then without wasting anytime Shisui's Sharingan spun and turned into a Mangekyo.
Staring Itachi straight in the eye, Shisui gave the command out loud.
"Never betray Sato sama, stay loyal to him alone."
Itachi's mind immediately changed, his memories and personality were the same but he had a new mission in life, serving his master Sato.
This was how Kotoamatsukami worked, if changing willpower wasn't overpowered enough, this justu does so without changing the memory and personality.
In war arc Itachi used Kotoamatsukami on himself with the command 'protect the hidden leaf' and all it did was give him a purpose.
How to protect the village was entirely upto him, the justu was so strong it didn't even force him to go to the hidden leaf to protect it, like normal genjutsu would.
Itachi went to Kabuto instead because he knew Kabuto was a threat to the whole world, which included the hidden leaf, technically he was protecting the hidden leaf as long as he defeated Kabuto.
Everything about this scenario was upto Itachi's interpretation, as long as he was following the given command he could do anything he wanted.
All this justu does was give someone a purpose in life, how they should fullfill that purpose was entirely upto them.
"Sato sama."
Itachi digested his new mission in life and got down on one knee, he bowed to Sato as a show of loyalty.
Yugito observed Itachi's calm face which hadn't changed at all, she wasn't sure if anything actually changed.
*Drip*
But then she found out that Shisui was holding his left eye which was dripping blood.
'So he did use the justu, I guess Itachi wasn't pretending, he really is a calm and collected guy.'
'I was too harsh on him then.'
Yugito shook her head and didn't speak, she decided to treat him better after this.
Sato who was silent all this while, smiled widely and clapped his hands.
"Get up Itachi, now that you have decided to follow me, I'll give you an official invitation to my squad."
Itachi got up and nodded calmly.
"I will join Sato sama."
"Excellent! Excellent! Hahahaha!"
Sato finally laughed without restraint, his villian like laughter was on full display but he didn't care.
He was way too happy right now, he had Itachi as his most loyal thug, this was Itachi!
Edo Itachi who was basically a theoretical healthy Itachi, defeated a full power healthy Nagato.
In the orginal story a sick Nagato used simple puppets of pain to wipe out the entire Hidden leaf village from existence.
A healthy Nagato with all his paths of pain combined into one was a beast, he trashed perfect jinchuriki Naruto and Killer B at the same time, then Itachi came along and practically one shot him.
Itachi was no joke, his genius knew no bounds, if he was the Indra reincarnation instead of Sasuke, the world would be saved three times over and nobody would even know.
"Hahahaha!"
"Ahahaha-"
*Bang*
Yugito could no longer take Sato's evil laugh and chopped him on the head, stopping him from continuing his laughter.
"Oww, you didn't have to do that sister."
Sato grumbled and rubbed his head, Yugito sighed and asked.
"What's next then?"
Sato stopped pretending to be in pain and straightened himself, he looked at Itachi and said seriously.
"Without Shisui your clan won't be rebelling tomorrow, we have to send Konoha an official letter before we can go back there as well, we got a little time to spare."
"So the first thing we will do is get your body checked, we will get you in perfect health."
Smiling widely Sato opened his arms, as if he was making a grand plan.
"Tell me Itachi."
"Have you ever heard of Tsunade Senju..?"