Naruto: My Progress in Konoha.

With that thought, Uchiha Haruki gathered a massive amount of Wind Release chakra, infusing it into his longsword while simultaneously cloaking his entire body with it.

A faint blue light emerged.

In a flash, Haruki executed his "Instant Sword Technique."

That's right—it was the Instant Sword Technique!

After developing this move previously, he had barely gotten to use it before his short blade was damaged, rendering the technique unusable.

Now that he finally had a good weapon again, there was no reason to hold back.

His figure blurred and became a mirage, appearing instantly in front of the Water-element mask creature, which was just about to ambush him.

Whoosh—

A cold flash of the blade.

Haruki's longsword slashed straight toward the mask portion of the monster.

That was its weak point. If he could destroy it, the creature would be eliminated, and Kakuzu would lose one of his five lives.

But things didn't go as planned.

Just at that critical moment, the black tendrils that made up the creature's body twisted and tangled together, forming a flesh wall that blocked Haruki's strike.

Squelch—

A heavy, rubber-like resistance met his blade.

It felt as though he were cutting into thick rubber—it was extremely hard to apply force.

Before he could pull away, the Lightning-element mask monster suddenly swooped in and spewed a bolt of electricity at him.

Haruki reacted swiftly, leaping back just in time to avoid being struck.

Not only that, he simultaneously completed a set of hand seals and activated the jutsu: Wind Release: Wind Blade!

Whoosh—

A transparent wind blade shot out at incredible speed, heading straight for the Lightning mask monster.

But just like last time, it swiftly dodged the attack with agile flight.

From a distance, Kakuzu was unfazed. His hands weaved signs quickly, and another mask monster released a jutsu: Fire Release: Searing Migraine!

A small fireball spat out, which, upon hitting the ground, erupted into a wave of scorching flames that swept outward.

Its power was significantly greater than when it had been used before.

Haruki hurriedly retreated, backing far away before performing a set of hand seals to cast Water Release: Water Formation Wall.

A surge of water shot up in front of him, forming a barrier that blocked the searing flames and leftover embers.

Truth be told, without activating the Mangekyō Sharingan, defeating these four elemental monsters was far from easy.

In his normal state, aside from Water, Fire, and Wind Release jutsu, his sharpest tools were swordsmanship and genjutsu.

His sword technique worked well against most shinobi—squishy targets that couldn't take a direct hit.

But these monsters were different. Their only weakness was the mask on their heads. Striking any other part of their body wouldn't do much damage.

That meant they only had to defend one area, and if needed, could even block with their tendrils like the Water-element creature had done.

That essentially rendered half of Haruki's sword skills ineffective.

As for genjutsu?

These monsters were entirely under Kakuzu's control. They had no consciousness—there was nothing to confuse or manipulate.

That left ninjutsu.

But setting aside the fact that he didn't know many jutsu, the ones he could use now had limited effectiveness due to elemental counterplay.

Given these three factors, it was clear: in his normal state, Haruki was being completely suppressed.

Unless he could directly attack Kakuzu's main body, he had no chance of winning quickly.

But Kakuzu wasn't giving him any chance to get close. In their earlier exchanges, Haruki had tried to approach multiple times, only to be blocked by the four mask monsters.

And even if he did get close, actually hurting Kakuzu was another matter entirely.

Kakuzu's main element was Earth. He could instantly use Earth Release: Earth Spear, which made his body as hard as steel. Physical attacks were nearly useless.

Only Lightning Release had the offensive power to bypass that defense.

But Haruki didn't know any Lightning Release jutsu!

That meant he had to rely on other methods, but Kakuzu's reaction speed meant there was at least a 50% chance he'd dodge.

In truth, that 50% estimate was generous. After realizing Haruki knew so much about his abilities, Kakuzu had been extremely cautious, avoiding direct combat wherever possible.

Haruki now regretted showing how familiar he was with Kakuzu at the start of the battle.

Had he played dumb, his situation might not be so dire now.

It all stemmed from his past-life memories. He'd assumed Kakuzu wasn't all that dangerous, based on what he remembered from the anime.

But now that they were truly fighting, he realized Kakuzu's actual strength was far beyond what he remembered.

To be fair, even during the fight with Naruto and the others, Kakuzu wasn't weak. He was ambushed by Kakashi early on, losing his Water mask. Then he was tricked by Shikamaru into using Hidan to destroy his Earth-element heart, losing his attribute synergy.

In the end, it was only due to carelessness that Naruto landed the Wind Release: Rasenshuriken, which ended the fight.

Otherwise, the outcome could have gone either way.

But now, Haruki was up against a fully-powered, extremely cautious Kakuzu.

It was obvious how difficult this battle truly was.

To put it bluntly, without activating his Mangekyō Sharingan, Haruki had almost no chance of winning this fight alone.

But using the Mangekyō came with a serious risk: what if he failed to kill Kakuzu in one shot?

If Kakuzu escaped, things would get very messy.

As a shinobi who had survived since the Warring States era, Kakuzu likely knew some of the deep secrets of the Sharingan, and may have even seen the Mangekyō before.

If he recognized it and lived to tell the tale, Haruki's secret could be exposed—and that was absolutely unacceptable.

As Haruki wrestled with indecision, Kakuzu had already sent his four elemental monsters after him again, unleashing wave after wave of ninjutsu to keep the pressure on.

Haruki shook his head, forcing himself to abandon those stray thoughts and focus on survival, fending off the attacks and looking for an opening.

At the same time, he began preparing to charge Kakuzu head-on, planning to mimic Naruto's tactics and use the ultimate jutsu:

Wind Release: Rasenshuriken.

Kakuzu might have five hearts, but if struck by this jutsu, even switching hearts wouldn't save him.

The chakra needles embedded in the Rasenshuriken would shred his body at the cellular level, making it impossible for him to manipulate chakra—even if he survived, he'd be helpless.

Fortunately, after rigorous practice, Haruki had leveled up his Rasenshuriken from Lv1 (100/200) to Lv3 (174/1000).

With that level of mastery, it was finally ready to be unleashed.