"Now listen, this is a special technique I developed. Uses bindings and pacts, consider it another form of Fuinjutsu, just without real seals."
"That certainly sounds interesting." Kakashi blinked, he honestly never heard of this form of Fuinjutsu.
With a little push Kakashi finally agreed to test out if he could turn off his Sharingan at will. It would be a miracle for him if he could. He at least didn't lose anything by just trying right!
However, contrary to his expectation, Sukuna, outside some simple kanji on his forehead protector, used no seals.
Instead, it followed a strange ritual.
Kakashi almost felt like he was signing a contract with a devil for something by the way the pink-haired boy was grinning.
Fortunately the binding vow, as Sukuna calls it, was easy enough.
Sukuna put two binding vows on him. At first he thought the boy was pulling his leg, perhaps that's what youngsters are into these days, but no…
It honestly worked to his amazement.
First vow… 'Temporarily lose any feedback and sight from his left eye. Until his own blood is drawn by an enemy in a fight and that is when his eyesight comes back.'
Kakashi almost immediately felt the siphoning of his chakra stop. In decades, for the first time, he felt his chakra not getting drained down a sink.
He almost inhaled fully as if he was doing this for the first time in ages.
And as the contract stated, he really did lose his sight from his left eye.
Kakashi had no idea how this binding vow works but he was gobsmacked if anything. He just hoped that the eyesight really comes back in a fight.
But, apparently, that was only the first part of it, there was more.
"Don't worry, your eyesight won't only come back but it will be even better. These binding vows work on the basis of risk and reward. You are taking a little risk, putting yourself in a handicap, by sacrificing your eyesight for most of the time. So when the eyesight comes back, it will also have a boost.
In your case, your Sharingan won't cost you that much chakra, it will be more efficient."
Kakashi's eyebrow shot up high, like finding that hard to believe.
'Understandable,' Sukuna thought.
Being able to make the Sharingan more efficient for a non-Uchiha was a big deal, this would break the assumption of people outside that Sharingan is useless unless you're an Uchiha. Because unlike the Byakugan, the Sharingan has an adverse effect if a non-Uchiha implants them in their eyes.
Kakashi himself was the biggest example.
As for how this binding vow helps Kakashi, it was obvious enough. Following Sukuna's streak of getting the most out of his binding vows, even if the said binding vow was for someone else— which by the way he had no idea could work for others but through his years of testing out his powers he learned— Sukuna cut off the constant siphoning of Kakashi's chakra through his Sharingan by cutting off his vision entirely.
By his own experience he also had learned that it's not only chakra but also the constant sensory data which fries a wielder's brain if the doujutsu is left open unchecked. So Kakashi also gets relief in that area.
But of course, that was only a side effect of his well-placed binding vow, the real benefit comes after.
Following the tradition of risk and reward, after putting himself at risk by half-blinding himself, Kakashi should get a reward, right.
With a simple trigger like an enemy drawing his blood in a fight, he regains his eyesight, although temporarily for that fight only, and his efficiency increases in his chakra manipulation. Making his chakra last longer, in terms of making his Sharingan more efficient during a fight.
Baffled, Kakashi still couldn't believe it.
However, without testing it out, saying anything was premature at best. So Kakashi could only wait.
However, he knew one thing, if this really works, then Sukuna might be a real genius. Not the kind who learns something fast, but the kind who invents an entirely new field of ninja arts, because he sure didn't see what Sukuna was doing here as Fuinjutsu.
One thing was certain, Sukuna Haruno was hiding more than he previously thought he would.
[Flash Back Ends]
…
For someone who covers his one eye all day long, even at sleep, losing his eyesight in one eye was no big deal for Kakashi.
It was a bit uncomfortable for sure but nothing that a Jonin like him can't handle.
However, what he wasn't ready for was when his Sharingan once again came to life.
It was a completely different feeling altogether, he felt like everything was clear to him, his Sharingan captured more than what he previously could. And his chakra.
Oh his chakra.
It was flowing steadily. Not chunking it down the drain. No, it was still expensive but at this rate, he can easily last through a long fight.
For a second, Kakashi all but lost his composure at how well it worked.
His posture straightened, his breathing steadied, and that single red eye focused sharply on Zabuza's every move. Even the mist around them felt lighter.
Zabuza clicked his tongue. "So you finally bring it out… fine. Come, Copy Ninja."
Kakashi didn't rush in blindly. Instead, he moved with calm, controlled steps. Savoring the Sharingan's lightness, smoother, almost natural. The strain that usually tugged at him was barely noticeable.
By no means was it gone, but this was bearable.
Zabuza swung his blade, expecting Kakashi to dodge late like before—but Kakashi was already gone.
In a blur Kakashi appeared behind him and kicked Zabuza in the back, forcing him forward. Zabuza spun, surprised but grinning. "Now that's more like it!"
He lunged with a wide slash. Kakashi's Sharingan traced the motion perfectly; he ducked under the blade and countered with a sharp uppercut to Zabuza's jaw. The swordsman stumbled, teeth clenched.
"Damn eye…" Zabuza muttered, shaking off the impact.
Kakashi didn't give him time to recover. He threw several kunai, each one aimed with precise timing. Zabuza blocked the first two with his sword, dodged the third, but the fourth grazed his cheek. The Sharingan was reading everything—every twitch of muscle, every shift of weight.
Zabuza growled and used Hidden Mist again, thickening the fog. "Let's see you copy this!"
This was a technique that his Sharingan couldn't do anything about. He had no other option but to wait, until Zabuza himself came swinging his giant blade.
He raised his kunai and blocked Zabuza's ambush strike perfectly. With the load Sukuna removed from his Sharingan, he felt his chakra reacting much faster.
Zabuza's eyes widened. "You… can still see me?"
Kakashi smirked. "Nah… I predict you."
He drove his knee into Zabuza's gut, pushing him back. Zabuza staggered but swung again in frustration. Kakashi sidestepped and caught Zabuza's wrist, twisting it just enough to break his rhythm. Using that moment, Kakashi landed a clean kick that sent Zabuza sliding across the bridge.
Zabuza dug his sword into the ground to stop himself. "Damn that Sharingan. I'll pluck that out from your socket by the end of this."
Kakashi held his kunai calmly, Sharingan spinning like a crimson storm. "Then you better be ready, cause I'm ending this fight."
Lightning came alive around Kakashi.
While he liked the feeling of his current Sharingan, he didn't know how long it would last. He'd rather not go testing right now.
~o~
A/N: What ya guys think, I really wanted to introduce binding vows for others as well, don't worry only Sukuna can do it, if you're worried about that, but this gives so much options for a character to grow. I always liked this concept of binding vows, it's pretty handy.
xxx
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