As the crystal completely merged into Nemuri Hachigo's body...
The originally calm, pale green nutrient fluid began to ripple with continuous vibrations.
Long ago, Aizen had already planted a time bomb within this perfect lifeform created through their joint collaboration.
The Hollowfication factor.
The nutrient fluid began to boil. The once clear liquid turned murky, and a dark red hue began to spread within the tank.
The eyelids of the curled-up sleeping beauty suddenly twitched violently.
Beep—beep—!!!
The alarm lights in the laboratory flashed, and a piercing siren erupted, instantly tearing the eerie silence to shreds.
"What's going on?!"
"High-energy reaction coming from the special laboratory! Spiritual Pressure levels are rising!"
"This is bad! It's the Director's Project Nemuri test subject! Who's on duty today?! Hurry! Cut off the Reishi supply pipes immediately!!"
The Department of Research and Development, already overwhelmed by the anomalies in Hueco Mundo, plunged into even greater chaos due to this sudden emergency.
The remaining researchers rushed frantically to the control consoles, desperately trying to contain the out-of-control power.
But it was too late.
Crack—!!
The specialized glass, capable of withstanding the impact of Captain-class Spiritual Pressure, became covered in a spiderweb of cracks the moment Nemuri Hachigo opened her eyes.
What kind of eyes were those?
No whites, no pupils—only two bottomless abysses of pitch black.
It was a chaos born from the mixture of a Soul Reaper's Spiritual Pressure and a Hollow's frenzy, catalyzed by Aizen's crystal.
Boom—!!!
A massive explosion echoed underground.
The incubation tank shattered completely, sending glass shards flying in all directions!
Nichika, however, had already retreated into the shadows long before the alarms sounded.
She gently drew the Zanpakuto from her waist, arcs of azure light flowing within her eyes.
"Manifest your might・Bishamon."
Following her chant, the Zanpakuto began to transform.
Her tsuba shifted into an octagonal piece of unrefined copper. A layer of pale purple-gold treasure light surged along the blade. Although the shape of the sword remained unchanged, the light made the blade difficult to see clearly, like looking at a flower through the fog.
Then, she placed her hand over the blade and spoke again. "Fukusekiten."
As soon as the words left her mouth, a heavy, purple-gold Spiritual Pressure spread from the blade, rapidly covering her entire body.
In the blink of an eye, Nichika's figure completely vanished from the laboratory.
'Phew... I absolutely cannot be discovered...'
She pressed herself tightly against the corner of the wall, her heart pounding wildly.
This was the Zanpakuto ability she had developed so far, capable of achieving near-perfect presence concealment.
Unless it was a Soul Reaper as powerful as her teacher, Aizen, no one would be able to detect even the slightest anomaly.
The smoke and dust cleared.
Nichika nervously swallowed hard as she saw the small figure suspended in midair, covered in severed cables.
Several researchers who had just rushed in saw this scene, but before they could even speak...
Roar—!!!
Nemuri Hachigo suddenly opened her mouth and unleashed a violent, savage roar.
A dark red ripple of Spiritual Pressure instantly swept across the entire laboratory.
'Oh no!'
Nichika, who had seen the anomaly three seconds into the future through her Future Sight, reacted swiftly, ducking low to dodge the bombardment of the ripple.
But the others were not so lucky.
"Ah! Damn it, it's Hollow contamination!"
"What is this?! Help!!"
Struck by the Spiritual Pressure ripple, the researchers' bodies began to undergo bizarre mutations.
White bone masks forcibly grew out of their faces, and their consciousness was instantly swallowed.
Hollowfication.
The crystal Aizen had given Nichika was actually a catalyst designed to stimulate the Hollowfication factor within Nemuri Hachigo.
It was now using Nemuri Hachigo as a vessel to spread the Hollow contamination throughout the entire space.
"Everyone, please step back."
A flat, emotionless command echoed from the entrance of the corridor.
The hem of a black Shihakusho fluttered slightly from her rapid approach as a woman's figure appeared at the laboratory door.
"This Spiritual Pressure composition... is a Hollow." She analyzed Nemuri Hachigo's condition with the calm precision of a machine.
She was the Vice Captain of the Twelfth Division, Mayuri Kurotsuchi's masterpiece.
Nemuri Nanago・Nemu Kurotsuchi.
She was originally supposed to be in the Department of Research and Development's maintenance room, monitoring the anomalies in Hueco Mundo according to Lord Mayuri's instructions.
But a few seconds ago, her neural link detected an abnormal Spiritual Pressure fluctuation inside the laboratory, belonging to her little sister, Nemuri Hachigo.
When she saw Nemuri Hachigo suspended in the air, exuding the aura of a Hollow and causing massive destruction, she pressed down on the wrist of one arm with her other hand.
A mechanical click sounded. "Unauthorized foreign intrusion detected. Hachigo's structural stability has dropped below the warning line."
"—Engaging combat mode."
Nemu's figure instantly vanished from her spot.
In the next second, she appeared directly above Nemuri Hachigo.
"Target locked. Commencing elimination."
Compressing all her Spiritual Pressure into her right foot, she brought down a devastatingly heavy axe kick, clashing directly with the rampaging Nemuri Hachigo.
Boom—!!
Countless unfortunate researchers suffered the consequences. To avoid being caught in the shockwaves of their battle, they had no choice but to flee in panic.
The entire underground laboratory was in utter chaos.
And this was exactly the opportunity Nichika had been waiting for.
Taking advantage of Nemu's entanglement with the rampaging Nemuri Hachigo, which drew everyone's attention, Nichika dodged the shockwaves of their continuous clashes and silently slipped out of the laboratory.
However, her goal was not to escape.
It was the Director's private archive, located even deeper within this laboratory level—a place ordinary researchers didn't even know existed.
'It can't be helped... Don't blame me, this is all for a better world...'
Recalling the map Aizen had given her, Nichika sprinted through the labyrinthine corridors.
Finally, she arrived before a pitch-black metal door.
"This is it... the final hurdle."
Nichika took a deep breath and pulled out a seemingly ordinary piece of white paper from her clothes, sticking it onto the forehead of the demon mask on the door.
Buzz—
The white paper instantly burned to ashes, transforming into a complex Kido formula that burrowed into the demon mask.
That was a forged pass, created when Aizen secretly analyzed Mayuri Kurotsuchi's Spiritual Pressure wavelength during their collaboration.
Rumble, rumble, rumble...
The heavy metal door slowly opened outward to both sides.
Behind the door was a rather small space.
There were no mountains of documents, nor were there the bizarre specimens one might expect.
The bookshelves on both sides held very few tomes and records, but each one seemed to exude a dangerous aura.
In the very center of the room, a transparent dome of light hovered in midair. Inside the dome floated an ancient scroll, sealed layer upon layer.
That was the item her teacher, Aizen, wanted.
Nichika quickly stepped forward, not daring to delay for even a moment.
She reached out, carefully touching the dome of light, only to find she couldn't advance a single inch further.
'...As expected, there's a special defense mechanism.'
She wasn't surprised. She simply gripped her purple-gold Zanpakuto, Bishamon, and spoke once more.
"—Hokyoten."
Buzz—
The heavy, oppressive aura surged once again.
The presence concealment shrouding Nichika vanished, transforming instead into a layer of golden light that eventually condensed into a small Treasure Casket Seal Pagoda in the palm of her hand.
As the pagoda spun, the dome of light began to slowly distort, becoming ethereal and illusory.
Seizing the opportunity, Nichika quickly reached out and grabbed the scroll.
The moment her fingers touched the scroll, a freezing sensation spread through her entire body.
"Got it..."
She didn't open it to look, nor did she have the time to.
However, out of the corner of her eye, she still caught a glimpse of a small line of text written in ancient characters at the scroll's seal.
Although it was just a glance, those two words seemed to possess some kind of magic, carving themselves deeply into her mind.
[The King's Seal].
"I'm sorry, Captain Kurotsuchi... I'm sorry, everyone at the Department of Research and Development."
Nichika quickly stuffed the scroll into her clothes, hiding it close to her body.
Dismissing the Treasure Casket Pagoda, she reactivated her presence concealment and turned to vanish into the shadows...
However, Nichika had been far too focused on stealing the scroll...
She completely failed to notice that in the corner of the laboratory, a precision camera was flashing with a red light, recording everything.
Mayuri Kurotsuchi, wearing his bizarre hat, stood in the monitoring room, drilling his long fingernail into his temple.
"It wasn't a waste to sacrifice Hachigo as bait. You've finally shown your fox tail, Aizen."
"...So this is your goal? You want to know the whereabouts of the King's Seal?"