Naraku Sora stared dumbfounded at Yamamoto, who was holding a charred longsword.
*Seriously, can someone tell me why this old man has Zanka no Tachi in his hands?*
*Is this even fair?*
He subconsciously glanced in the direction of Aizen and Urahara Kisuke.
The former calmly turned his head away, seemingly observing the residual Reishi in the air.
The latter grinned, full of schadenfreude, acting as if he had already cast aside life and death.
To prevent Yamamoto from causing too much destruction, Aizen and Urahara Kisuke had discussed temporarily sealing Ryūjin Jakka long before the experiment began.
For this specific purpose, they used the Hōgyoku to create an Arrancar named the Prince of Extinguishing Flames.
It was more or less the same as the Prince of Extinguishing Flames in Naraku Sora's memories, but it lacked any mobility whatsoever; it was born purely to seal Ryūjin Jakka.
He had watched with his own eyes as the two of them sealed Ryūjin Jakka.
*But now, could someone please explain what the hell that thing in Yamamoto's hand was!*
Although he felt somewhat indignant, Naraku Sora knew very well that no matter how scheming Aizen was, or how brainless Urahara Kisuke could be, neither of them would joke around with something like this.
*Therefore, it had to be that old geezer Yama's fault!*
At this thought, his gaze suddenly turned fierce, and a voice like resonating metal echoed across the wasteland.
"Bankai—"
"Vajrayati, Karma and Consciousness Coexist!"
A massive red and black pillar of light erupted, becoming the most dazzling sight in Hueco Mundo. The sea of fire above the canopy was forcibly shattered and swept away.
Scorching heat rose, and an aura of destruction permeated wildly, obliterating the drifting dust.
This time, it wasn't just the people present; even Las Noches, thousands of kilometers away, sensed the anomaly.
The previously mild climate had somehow been replaced by searing heat. Every breath felt like a hot knife piercing the throat, the burning pain cutting deep.
The expressions of the Espada turned extremely solemn.
The moment both sides unleashed their Bankai, it completely redefined their understanding of power.
They had thought the demonic forms from earlier were the limits of those two, but unexpectedly, that was merely the tip of the iceberg.
Feeling the high temperatures permeating the air, deep horror flashed in the eyes of the Hollows.
If it was like this tens of kilometers away from the battlefield, what kind of scene must it be at the center where the old man and the youth were facing off?
Would Hueco Mundo really not be destroyed in their battle?
For a moment, intense worry welled up in the hearts of the Espada.
The Hollowfied Yamamoto gripped his charred longsword. Black ash fell from the blade, and a thick wisp of blue smoke slowly rose.
Opposite him, Naraku Sora held a heavy blade evolved from the stars. Pitch-black branches grew from the blade, continuously extending and intertwining outward.
An abyss-like crimson spread from the center, emitting a distorted light.
This was a true peak state in every sense, an unprecedented full-power outburst.
Feeling a sense of power he had never experienced before, with endless Reiatsu filling his limbs and bones, Naraku Sora flashed a ferocious grin at Yamamoto, a trace of white steam escaping from between his teeth.
"You think I'll avoid your edge?"
The moment his words fell, he raised his right arm, pulling along explosive winds as he slashed forward.
It sounded like the booming of heavenly drums.
The earth beneath their feet let out an overwhelmed wail in the face of this strike, the wasteland seemingly torn apart down the middle by an invisible giant hand.
Waves of sand surged to both sides, forming silver waterfalls that connected heaven and earth.
Watching the giant, heavy blade arrive in an instant, Yamamoto cracked his mouth open, revealing a ferocious and brutal smile identical to Naraku Sora's.
Zanka no Tachi, West: Zanjitsu Gokui!
Fifteen million degrees.
This was the temperature of the sun's core, a temperature that reduced all matter to nothingness, a temperature sufficient to evaporate all the moisture in a world.
Flames violently erupted from his scar-covered body. It wasn't just burning; it was cloaking—
Driven by instinct, Yamamoto transformed himself into a walking sun!
The raging flames turned into a tidal wave, mercilessly scorching everything. The silver sand below showed an unstoppable trend of melting.
The next moment.
The two figures, radiating overwhelming visual effects, slammed into each other fiercely.
At the instant of collision, sound seemed to be completely erased.
The air was compressed into a visible white halo, rapidly expanding in all directions.
Wherever the halo passed, sand dunes were instantly leveled, rocks were crushed into powder, and all elevated terrain was flattened by this pure shockwave.
Immediately after, countless sound waves suddenly erupted, overlapping with one another to form a pure symphony of destruction.
Boom!!
Yet another unreserved, violent collision caused the entirety of Hueco Mundo to boil. Scalding, fiery winds rose from the ground, dyeing the night sky crimson.
The thin air vibrated and rioted, with countless scorching air currents echoing between heaven and earth.
At this moment, both sides had pushed their defenses to the absolute limit, integrating technique into instinct and letting it drive them.
In this purest form of close-quarters combat, every clash erupted with a deafening roar. The shockwaves surged, lifting massive shadows like ocean tides.
Flames scorched, and lightning detonated.
The two transformed into tireless machines. Every swing of their blades aimed at the other's vital spots, as if they were mortal enemies.
The pitch-black branches and the charred blade bit into each other tightly, two completely different powers clashing madly at the point of contact.
The world lost its color.
Only black-red and crimson-gold remained, intertwining, tangling, and eroding each other.
Before the two completely erupted, Urahara Kisuke had already taken the battered remnants and quickly retreated.
Yet even so, they were still caught in the shockwaves, ending up covered in dirt and ash.
The Espada were nearly buried by the silver sand.
Aizen, on the other hand, observed the two constantly colliding streaks of light and felt a bit of a headache.
The current situation had indeed exceeded their original expectations.
It was just like during his own Hollowfication experiment.
No one had expected that, while in an instinctual state, Aizen could not only maintain his ability to think but even cast Kidō.
It was as if Kidō had been carved into his very bones.
The current Yamamoto seemed to be the same.
But upon closer inspection, there was a massive difference.
Ryūjin Jakka had indeed been sealed; there was no doubt about that.
Before the experiment began, he and Urahara Kisuke had repeatedly confirmed that the Prince of Extinguishing Flames' ability was extremely stable and would absolutely not fail.
But now, Yamamoto had somehow pulled out a Ryūjin Jakka from nowhere and even directly released his Bankai.
As for the Prince of Extinguishing Flames sealed in Las Noches, after communicating with the Arrancar left behind to guard it, it was confirmed that it had been burned to ashes, not even leaving a complete corpse behind.
Separated by thousands of kilometers, he was still able to forcibly break the seal.
Aizen prided himself on his abilities, but even he couldn't achieve such a feat.
As for how Yamamoto managed it, he could only think of one possibility.
That was Zanpakutō fusion.
Aizen had previously researched related concepts.
In his view, the Zanpakutō, as a Soul Reaper's primary weapon, allowed them to rapidly grow stronger when they were weak, completing a leap in power.
Which was the so-called Shikai and Bankai.
But once the power of Bankai itself was thoroughly comprehended, the existence of the Zanpakutō would instead become a shackle.
Only by completely fusing with this power, which originally belonged to oneself, could a new path be forged.
Regarding this, Aizen already had a few ideas.
However.
The potential of this Head Captain Yamamoto seemed to be far higher than previously anticipated.
As a terrifying existence who had dominated the Soul Society for thousands of years, his talent was obviously unquestionable.
The only reason he had remained at the level of a Soul Reaper was entirely due to the lack of assistance from scientists like himself or Urahara Kisuke.
Of course, it also had something to do with his pedantic and stubborn personality.
If not for Naraku Sora's subtle influence, even if Yamamoto knew that Hollowfication could bring him earth-shattering changes, he would absolutely never accept it.
In short, to reach this point today, every single factor was indispensable.
Now, it all depended on whether that guy Naraku Sora could hold on.
Riiip—
The sound of tearing flesh was particularly clear. During the stalemate of their blade clash, driven by instinct, Yamamoto's left hand shot out like lightning, forcibly tearing off one of his rebellious disciple's arms.
Terrifying heat erupted, instantly burning it to ashes.
Fortunately, this level of injury was nothing to Naraku Sora.
As long as he applied Reiatsu to his High-Speed Regeneration, he could regrow an arm in the blink of an eye.
It was unknown how long their battle lasted, but even someone as formidable as him felt a trace of fatigue.
In contrast, Yamamoto opposite him still maintained a vigorous posture, showing not the slightest sign of exhaustion.
He was fighting with the relentless ferocity of a man possessed.
Although he had been at a constant disadvantage, mercilessly battered by Yamamoto, he could still barely hold on.
He just wasn't quite sure when exactly Yamamoto would subdue the 'Hollow' within his heart.
If this dragged on any longer, he might be fine, but Hueco Mundo would collapse first.
Feeling the scorching heat in his nasal cavity, Naraku Sora grimaced, and his figure vanished from the spot.
When he reappeared, he was already behind and to the side of Yamamoto.
Vajrayati swept horizontally, wrapped in black and red lightning, slashing toward the old man's waist.
Yamamoto abruptly turned around, swinging Zanka no Tachi diagonally backward. The charred blade perfectly blocked the trajectory of the incoming sword pressure.
A ferocious curve was outlined on the bone mask. His golden, slit-like pupils instantly locked onto Naraku Sora's figure. Spreading the five fingers of his left hand, he pulled the fiery winds and instantly clenched them into a fist.
A deafening roar resounded.
A figure streaked across the sky like a meteor, blasting a massive crater thousands of meters in diameter into the devastated earth.
But at the exact moment the two created distance, Aizen seized the opportunity and instantly followed up with crowd control.
"Bakudō #99: Kin!"
Leather straps and nails appeared out of thin air, directly binding Yamamoto's hands.
"Bakudō #99, Part 2: Bankin!"
"First Song: Shiryū."
Reiatsu as vast as the sea surged, transforming into fabric strips imbued with powerful binding force. They wrapped around and sealed Yamamoto's body, instantly restricting his Sonído.
"Second Song: Hyakurensan."
Hundreds of iron bolts materialized out of thin air, piercing directly through his Hierro and stabbing deep into his flesh.
Aizen's pupils turned a brilliant golden yellow.
"Final Song: Bankin Taihō!"
A torrent of Reiatsu descended from the sky, condensing under the night canopy into a towering stone monument that crashed down heavily.
Countless clouds of dust rose, blotting out the sky and the sun while instantly spreading for tens of kilometers.
Watching that exaggerated display, Urahara Kisuke couldn't help but click his tongue.
As a genius who was equally accomplished in the field of Kidō, he knew very well just how massive an amount of Reiatsu was required to achieve this level.
It seemed like there were only two monsters blasting each other on the battlefield, but in reality, Aizen was not inferior to that master and disciple duo in the slightest.
It was just that their combat styles were quite different.
Yamamoto and Naraku Sora were cut from the same cloth; both had a reckless, death-defying fighting style, their minds filled only with the thrill of battle.
Aizen, on the other hand, excelled at calm processing, preferring to exchange the minimum effort for the maximum gain.
He originally thought the number ninety-nine Bakudō could suppress him for a while, but in the next second, the massive stone monument vanished into thin air, as if it had been completely erased.
Under the iron-red sky, Yamamoto walked forth, resembling a humanoid natural disaster.
He paid no mind to Aizen, who had just attacked, and was solely focused on making trouble for Naraku Sora.
It was as if he only had eyes for this one person.
Seeing Yamamoto appear before him once again, Naraku Sora couldn't help but feel a profound sense of exasperation.
*This old geezer probably hadn't lost his mind at all; he was just trying to take advantage of this opportunity to ruthlessly bully his poor, weak disciple.*
Soon, the charred longsword and the black-red blade clashed once again. Countless sparks erupted from the impact, directly igniting the surrounding wasteland.
Looking at the bone mask right in front of him, Naraku Sora gritted his teeth. Squeezing out his last ounce of Reiatsu, he braced against Zanka no Tachi while suddenly pulling his left arm back.
Right at that moment, cracks appeared on the bone mask opposite him. The gold in his eyes gradually faded, and that familiar gaze returned.
A trace of a gratified smile surfaced on Yamamoto's face:
"Brat, I have completed the Hollow..."
However, before he could finish his sentence, a fist magnified infinitely, instantly occupying his entire field of vision.
Then, it smashed solidly into that completely unprotected face.
Boom—
Hueco Mundo shook from the impact!