The stench of decay and stagnant moisture permeated the air, thick with a sickly green darkness reminiscent of the deep sea.
This was the subterranean depths of the Matou Residence, perched on a isolated hill town, where the family’s forbidden chambers lay hidden deep underground.
Looking at the grim spectacle before her, Sakura covered her nose, her voice trembling violently.
“…G-Grandfather, what is this place? What are these creatures?”
A few meters ahead of the young girl lay a massive, yawning abyss.
Within the pit, countless black shadows squirmed in a dense, undulating mass.
Extremely hideous in appearance, with invasive, leech-like mouthparts, they moved in a sickening slurry of biological fluids.
It was a shifting ocean of parasitic entities, gathered together like a heavy, suffocating carpet.
The decaying chamber emitted a sharp, pungent odor of putrid essence, accompanied by a collective, spine-chilling hum.
These were the Crest Worms bred by Zouken—monsters designed to crave human vitality, magical energy, and spiritual essence.
Once infested by these parasites, a subject’s internal circuits would be systematically rewritten, their independence stripped away as the swarm established absolute control over their nervous system and vital organs, eroding both mind and body until nothing remained but a hollow vessel for the family’s craft.
The current accumulation within this chamber represented over two hundred years of systemic cultivation.
As per Rhodes’s precise coordination, Zouken had brought out the entirety of his accumulated research tonight to prepare a definitive trial for Sakura.
“Hmm. Then, let us begin,” the old man rasped.
“…Grandfather, no,” the girl whispered.
Listening to Zouken’s deliberate, unyielding explanation, tears welled in her eyes, and she let out a desperate, strained cry.
“If you harbor resentment, blame your arrogant father who placed his trust too blindly in flawed alliances… Oh, by the way, Tohsaka Tokiomi is no longer your father, is he? Hahahaha, ah ha ha ha ha ha ha!”
The old magus cackled, stepping closer to her side.
“Go, and fulfill your purpose within the Matou line.”
“No!!!”
The girl shrieked, her strength failing as she collapsed to the cold stone floor.
“Oh dear, oh dear… Sakura, do not complicate matters for this old man,” Zouken muttered.
Striding forward, he seized her by the hair and dragged her directly to the edge of the precipice.
“No, no, no… Stop—!!!”
With a sudden, sharp movement, her small frame was cast down into the squirming depths of the chamber.
The moment she broke the surface of the swarm, the parasites, sensing a prime catalyst, emitted a chorus of piercing, erratic chirps.
The hideous mass surged forward, rolling and writhing as it sought to completely engulf the girl.
To endure, to break, and to be remade into the ultimate vessel for the Matou—Zouken’s face contorted into a grotesque smile of anticipation.
Then—
“…Hmm?”
The grin on the old man’s lips vanished, replaced by a sudden, unnatural silence that rippled through the subterranean air.
“—Hoo.”
Suddenly, a distinct sound of laughter emanated from the center of the dark abyss.
It was a clear, melodic laughter, far more chilling than the collective rustling of the swarm.
The sea of corruption abruptly violently convulsed.
Severed fragments of the parasites erupted into the air like a localized tsunami as the surrounding swarm frantically attempted to scatter in sheer panic.
“…What? What is the meaning of this?!” Zouken stared intently into the depths of the pit.
From the exact point where Sakura had fallen, several glowing, blue-black spiritual ribbons shot skyward.
Spinning with the centrifugal force of razor-sharp blades, they systematically shredded every entity in their path.
“Sakura! What are you doing?! What is that power?!”
When the figure emerged from the remnants of the swarm, her appearance had fundamentally shifted.
While her stature remained unchanged, her short dark hair had transformed into a vibrant aquamarine, and her dark pupils were now stained a deep, brilliant crimson.
“Vessels that have degraded to the absolute bottom hold no intrinsic value,” the girl remarked, looking up at Zouken with an expression of supreme mockery.
Though her form belonged to Sakura, the presence animating it was entirely distinct.
“—”
The moment their gazes locked, Zouken’s breath caught in his throat.
He recognized that exact quality of expression.
He had seen it very recently.
Those bottomless, detached eyes—they were identical to Rhodes’s.
“The manifestation is complete,” she murmured, a dark aura flaring around her.
…
Zouken’s intellect and perception were exceptional by mortal standards; he possessed the insight to recognize spiritual aptitude and develop it ruthlessly.
His ultimate miscalculation was not the malice of his methods, but the fact that his comprehension remained strictly bound by conventional mortal laws.
Sakura’s latent compatibility far exceeded the boundaries of what the old magus could control.
A year ago, Rhodes had utilized his own anomalous nature alongside the girl’s baseline structure to anchor a specific summoning—the Divine Spirit, Kama.
Because her spiritual origin possessed a rare, paradoxical alignment with Sakura’s core, the unconventional invocation had succeeded.
Since she was not a standard Servant tethered to the local ritual, she had remained completely dormant within the girl’s vessel to conserve energy, easily eluding even Zouken’s decades of scrutiny.
But tonight, the old man had unwittingly presented her with a supreme concentration of stored magical energy: two centuries worth of highly concentrated familiars.
To an entity of her nature, this massive reservoir was a feast, more than sufficient to sustain an absolute manifestation.
…
The dark blue ribbons, trailing arcs of ethereal flame, danced wildly through the subterranean chamber, harvesting the condensed energy.
Even as the remaining parasites attempted to scale the high stone walls to escape, they were completely helpless.
The situation had inverted into a unilateral annihilation of the Matou’s accumulated power.
“Hahahahaha! To think grandfather secured such a dense collection of raw energy! Splendid! Truly splendid!—”
“—Ah, ahahahahahahaha!”
“Wait… wait, Sakura, cease this at once—”
“Ah. Has the process already commenced? Makiri, I recall instructing you to wait for my arrival before initiating the sequence.”
A calm voice echoed from the entrance of the chamber.
Zouken turned his head in a panic.
Rhodes, the primary architect of the entire arrangement, was strolling leisurely into the room, casually finishing a light snack.
“Hey! Rhodes! What is the meaning of this?!”
“Hmm? This?” Rhodes glanced down at his hands.
“Just a light refreshment before the main event.”
“…!?!”
“My, looking at me with such intensity won’t make me share, you know?”
“This old man is demanding to know why Sakura has manifested such an anomaly!” Zouken shrieked hysterically.
“Makiri, you explicitly granted me total authority to direct her development over the past year. My apologies; I may have been slightly thorough and inadvertently brought her latent aspects to the surface.”
“You… you are insane! How could any conventional training result in this?!”
Rhodes shrugged, walking to the edge of the pit and peering down into the chaotic storm of energy.
“My word—it really is quite a spectacular clearing of the board.” He watched with detached amusement as the divine entity systematically dismantled the remaining network.
“Ah… Senior, you’ve finally arrived,” Kama noted, pausing her movements to look up at him.
“Care to step down and join the festivities?”
“—Not in this lifetime,” Rhodes replied with a look of mild distaste.
He stepped back from the ledge, walking over to Zouken, who had completely ceased rational thought, and placed a steady hand on the old man’s shoulder.
“Makiri, surely this much isn’t the absolute limit of a two-hundred-year lineage?”
Zouken, snapped back to reality by the gesture, began to stammer incoherently.
“Wait… wait, wait!! Rhodes, no, stand down! We have a binding pact, you cannot initiate harm against me, I have fulfilled every condition—”
“And you have done exceptionally well, Makiri. The Matou family has successfully fostered an extraordinary development; you should have absolutely no lingering regrets. Now, it’s time to perform your final contribution to the lineage.”
With a sudden, deliberate movement, Rhodes delivered a sharp kick to the old magus’s back, sending his frail form tumbling over the edge and into the abyss below.
Go on.
Provide the final catalyst for your masterpiece with your own essence.
“Oh, look—Grandfather decided to join in,” the young deity smiled gracefully, lifting her slender wrist.
Several shadowy tendrils surged from the base of the pit, instantly pinning Zouken’s limbs mid-air.
Before a single cry could escape his throat, the concentrated force tore the old magus’s physical avatar into spiritual remnants, scattering them into the fading embers of the swarm.
Thus, within the silent depths of the Matou estate, only the two anomalies remained.
“Fuhahaha, hahahahahahahahaha—”
The dark flames flickering over the cleared chamber seemed to celebrate the definitive shifting of the paradigm.