Kakuzu made his claim with confidence because he had mastered a secret technique called Earth Grudge Fear.
This technique allowed him to incorporate the hearts of others into his body. In addition to extending his life, it also gave him access to the nature transformations that the original owners of those hearts naturally possessed.
Over the years of his long ninja career, Kakuzu had continuously replaced his hearts, and each one now belonged to a master of a different nature transformation.
As a result, he had also become proficient in the five basic nature transformations, mastering the Five-Element Ninjutsu to perfection.
Thus, he could confidently say:
"No one understands Five-Element Ninjutsu better than I do."
He had expected Natsuhiko's technique to be as strange as the previous one, but it turned out to be a standard Five-Element Ninjutsu, which made him relax a little.
"And he even announced the name of his technique in advance. It seems he lacks combat experience," Kakuzu thought to himself with a condescending smirk, lightly raising his hand.
Suddenly, a mass of tentacles emerged from the cracks in his arm, covering it entirely. Finally, a strange mask appeared in front of his palm.
Fire Release: Intelligent Hardwork!
The mask's crimson mouth opened abruptly, and scorching flames gushed out like a tidal wave, heading straight toward Natsuhiko's Great Vacuum Sphere!
Fire overcomes Wind!
The five elemental techniques have relationships of mutual restraint.
Since Kakuzu had fully mastered all five nature transformations, he could always choose the most suitable technique for battle.
To put it in Pokémon terms, he was like a budget version of Arceus.
Especially in this case, if the power of Fire Release far surpassed Wind Release, it was very likely that the fire would borrow the wind's strength, using Natsuhiko's Wind Release to fuel his own Fire Release and turn it against him.
Natsuhiko probably never expected that his powerful wind technique would become his own undoing.
Kakuzu, now fully aware of the danger of elemental battles, suddenly narrowed his pupils.
At the moment when the two techniques collided, he saw Natsuhiko's Great Vacuum Sphere, which should have been at a disadvantage, tearing through the sea of fire and continuing to fly toward him!
Impossible!
What kind of reverse-elemental master is this?!
To counteract an element with a weaker one and defeat the enemy's technique, one must far exceed the opponent in chakra quality and skill!
And this Fire Release: Intelligent Hard Work was a technique Kakuzu had spent years refining. Although it appeared simple, it had reached a level of sublime craftsmanship.
Moreover, the heart he used for this technique came from a Fire Release expert he had carefully selected. In terms of fire chakra quality, it shouldn't lose to anyone!
So no matter how he thought about it, his fire technique shouldn't have lost to Natsuhiko's wind technique!
His prideful technique had been effortlessly shattered, and even the experienced Kakuzu momentarily lost his focus.
As a result, he missed the window to dodge the attack still coming toward him.
Boom!
The next moment, Natsuhiko's Great Vacuum Sphere struck Kakuzu directly, causing an explosion of smoke and water.
Wait, something felt off.
Kakuzu's figure, with his arms crossed in front, quickly rushed out of the smoke, seemingly unharmed.
What was different this time, however, was that his body was wet…
"Damn it, it was Water Release!"
Lowering his arm, which glimmered with a dark sheen, even the usually composed Kakuzu couldn't help but curse!
Now he understood: Natsuhiko had used the projection of a Wind Release technique to lure him into using Fire Release, while secretly using a Water Release technique to counter it.
This allowed him to turn the tables with a weaker technique!
This wasn't reverse-elemental mastery at all—it was just basic strategy!
This guy was clearly different from an ordinary ninja, even able to play around with the most orthodox Five-Element Ninjutsu!
At that moment, Kakuzu couldn't help but feel a strange sense of weariness, wondering if he was getting too old to keep up with the thinking of younger people.
Natsuhiko, unaware of the mental blow he had dealt to Kakuzu, felt a pang of disappointment when he saw Kakuzu emerge unharmed.
After all, his one-hit kill techniques worked best the first time.
Once the enemy was on guard, it would be much harder to land a successful attack.
So, since this time he couldn't severely wound Kakuzu, it would be even more difficult to find another opportunity later.
At the same time, Natsuhiko noticed the faint traces of black fading from Kakuzu's arms.
So he used the Earth Spear technique?
Earth overcomes Water!
Although Earth Spear hardened the skin for physical defense, it also provided strong protection against Water Release. No wonder Kakuzu was unharmed.
But this also meant that Kakuzu's Earth Release heart was still intact, which was troublesome…
From the start, Natsuhiko had feigned death, hiding out of sight, to first eliminate Kakuzu's most troublesome Earth Release heart!
With Earth Spear's defensive power combined with Kakuzu's immortality, his survivability reached an infuriating level.
Under normal circumstances, Kakuzu would go to great lengths to protect his original heart, which meant that to truly kill him, the other four hearts had to be destroyed under the protection of the Earth Spear first!
In the original story, if it weren't for Shikamaru taking advantage of Hidan's blunder and using the curse to destroy Kakuzu's Earth heart, Kakashi and the others might have been killed before Naruto arrived.
It could be said that only with Earth Spear and Earth Grudge Fear combined did Kakuzu reach his full form, the reason why he had roamed the ninja world for so long without ever losing.
Lastly, there was the fact that Lightning overcomes Earth.
Through his prototype analysis of other people's chakra natures and his extensive research, Natsuhiko had already mastered four of the five nature transformations.
The only one he hadn't mastered yet was Lightning Release…
So, with Kakuzu now on guard, Natsuhiko had no good way to break through his defensive "turtle shell."
That was why Natsuhiko had carefully planned to eliminate the biggest obstacle to defeating Kakuzu from the outset.
If he had succeeded, he might have even been able to keep Kakuzu there permanently.
Unfortunately, Kakashi had turned out to be the unexpected variable.
Who would have thought he'd be so bold, challenging a high-level foe like Kakuzu when he was still a low-level ninja?
When Natsuhiko saw Kakashi being grabbed by the throat, he didn't dare bet that Kakuzu would spare him, so he had no choice but to strike first.
Although Kakashi should be waiting by a campfire on the brink between life and death, Natsuhiko thought it would be best not to let them reunite so soon...
After all, Kakashi was someone he brought out, and returning him in one piece was part of his responsibility as a teacher.
However, with this hasty strike, even though he landed a hit, Kakuzu managed to avoid a critical blow.
Although Natsuhiko felt like he had struck the heart, the current situation clearly indicated that it wasn't the heart that performed the Earth Release: Earth Spear, nor the one that performed the Fire Release: Intelligent Hardwork...
Regardless, Natsuhiko gained some advantage in their previous exchange, so he pressed on. With a clap of his hands, he prepared to launch another attack.
Again?
Kakuzu, having just emerged from the smoke, couldn't help but feel somewhat humiliated.
After all, just moments ago, he was confidently certain of victory, only to be slapped in the face by reality.
Luckily, he hadn't said anything out loud...
But such a situation wouldn't happen again.
Natsuhiko's tricks could only work once. After witnessing them, Kakuzu wouldn't fall for it so easily!
So, as soon as Kakuzu saw Natsuhiko's movement, he halted, focused his mind, and kept a close watch on his opponent. He intended to identify the technique Natsuhiko was using and then deliver a counterattack, tit for tat.
Then, he heard Natsuhiko shout once again: "Earth Release: Water Chaos Wave!"
Immediately after, Natsuhiko spat out a huge fireball from his mouth!
"…"
"…"
"…"
For a moment, Kakuzu's brain froze.
Fortunately, at the last second, he managed to react—he suddenly threw himself to the side, dodging the "fireball."
Boom!
The "fireball" whistled past, instantly blasting a large tree behind him into pieces!
It seemed that although the prefix was Earth Release, the name was Water Release, and it looked like a Fire Release technique, it was actually a Wind Release...
Seriously!
Why don't you just throw in Lightning Release as well?
Kakuzu mentally cursed.
He finally realized he had a weakness.
—That was his brain!
Though he didn't know how Natsuhiko did it, his swift, seal-less techniques left Kakuzu with little time to react.
Moreover, the techniques Natsuhiko used were of the fast-moving variety.
So, if Kakuzu didn't immediately counter with a technique that could suppress Natsuhiko's, he wouldn't be able to respond in time.
What made it even worse was Natsuhiko's low-level tactic of shouting out the wrong technique names before attacking. It actually put additional strain on Kakuzu's brain and slowed his reaction time.
It was like writing information in one color of ink but having the words refer to different colors, and then asking someone to identify the color of the font. A simple task made difficult by the interference.
And with Kakuzu's unchanged brain—just his heart replaced—his elderly mind wasn't exactly equipped to instantly figure out Natsuhiko's techniques...
Naturally, Natsuhiko wasn't about to play by the rules of ninja ethics. He clapped his hands again, ready to play another guessing game with the old man.
Kakuzu, a battle-hardened veteran, had already adjusted his emotions by now.
He had encountered situations where he couldn't gain the upper hand with techniques before, and this was the time for close combat.
This was where Kakuzu excelled.
While none of his abilities were godly, they were all at Kage level.
So, by using his strengths to attack his opponent's weaknesses, and with his immortal body, the one who would have the last laugh would still be him...
(End of Chapter)