"Where is she?!"
"Where is she?!"
"Where is she?!"
Scene after similar-yet-different scene flashed past Emiya's eyes in rapid succession.
He'd long since lost count of how many windows he'd leaped through across countless connected spaces.
Even the creator of this chaotic realm struggled to follow Emiya's erratic jumps from one scene to the next.
Every time it pinpointed Emiya's location, he slipped away like an eel, leaping into another section.
This labyrinth—originally designed to aid demons in battle—now hindered its master from accurately tracking Emiya's movements.
Yet, the Infinity Castle wasn't truly infinite. Its creator wouldn't isolate herself completely from other areas. On the contrary, being at the very heart of the Infinity Castle meant her location must connect everywhere!
"Found you!"
At last, Emiya spotted her—a female demon with long, black hair covering her eyes beneath heavy bangs, calmly seated in a kimono. She gently strummed her biwa, seemingly unbothered by Emiya's sudden appearance.
Could this be a trap?
Emiya hesitated momentarily, wary of the unnerving composure the demon displayed. He could close the distance and sever her head in an instant, yet past experiences warned him that demons' Blood Demon Arts were rarely straightforward.
Whoosh—!
As if confirming his fears, a sharp whistle pierced the air above Emiya.
A sliding door—common in Japanese architecture—hurtled down upon him with lethal force, carried by a fierce gust of wind.
Under such immense speed, even a wooden door became a deadly blade capable of slicing his head clean off.
Emiya instantly sensed the demon's control had grown vastly more precise. Previously, attacks involved entire structures haphazardly charging at him, but now individual objects within rooms were turning into lethal weapons.
"[Beast Breathing—First Fang: Pierce]!"
With a swift twist, reminiscent of a crocodile dodging prey, Emiya narrowly avoided the sudden strike.
Firmly gripping his projected serrated Nichirin Blades, he pressed his feet against a window behind him and lunged forward.
He streaked toward the female demon like silver lightning.
Since he'd already projected Hashibira Inosuke's distinctive blades, Emiya chose to fully exploit Beast Breathing techniques for now.
Of course, nothing prevented him from combining these with his own Sword Breathing techniques.
BOOM—!
A deafening crash echoed through the room as splintered wood burst into fragments, whipping up a fierce gust of wind from the impact point.
But as Emiya observed the empty ground beneath him, he immediately recalled his earlier battle with Mukago.
Nakime, with far superior spatial control, naturally had the ability to teleport herself—instantly, effortlessly, and across longer distances.
Indeed, Nakime could teleport others as well as herself. Against typical Demon Slayers, she could easily defeat them without harm. Even Hashira-level fighters risked being worn down slowly, unable to close in until they fell victim to her relentless spatial manipulation.
But Emiya had already faced—and slain—a demon with spatial powers once before.
Nakime's personal combat strength was even weaker than the Lower Moon Mukago. Without her overwhelmingly powerful Blood Demon Art, she wouldn't even qualify as an Upper Moon.
In fact, she currently wasn't one.
As Muzan's personal attendant who managed the Infinity Castle, she rarely engaged in actual battle. Her physical strength was merely the result of the copious amounts of Muzan's blood she'd absorbed.
"[Sword Breathing—Wind Form: Dust Whirlwind Cutter]!"
Before Nakime could even react, having teleported just a short distance behind Emiya—
Whoosh—!
—Emiya appeared at her side like a furious gust.
Having already pushed his legs beyond their limits by using Agatsuma Zenitsu's original Thunder Breathing form, Emiya knew he could no longer rely on lightning-speed movements.
Perhaps he could force himself through one more burst of Thunderclap and Flash, sacrificing his legs' remaining strength—but in this unpredictable place, facing unknown demons with bizarre powers, losing mobility would be suicide.
So Emiya settled for an alternative, slightly slower yet still swift technique.
Though his current speed was a far cry from Thunder Breathing's instant movements, Nakime stood frozen, either stunned by the speed of his approach or shocked that he'd immediately pinpointed her new location.
Emiya's serrated Nichirin Blade slipped smoothly into her neck—so easily that Emiya almost doubted the sensation.
Whoosh—!
But at that very instant, a crushing pressure descended upon the entire chaotic space. It was as if the air itself grew heavy, pressing down with suffocating intensity.
The Nichirin Blade already embedded in Nakime's neck halted instantly, frozen in place by the overwhelming aura.
Emiya sensed immediately that someone terrifyingly strong had arrived.
"If you died, Lord Muzan would be most displeased."
A tall samurai stepped forth, clad in a purple, serpent-patterned kimono paired with dark hakama. His long black hair was tied into a high ponytail, his face marked by three pairs of cold, indifferent eyes.
Casually gripping Nakime by the back of her collar, he effortlessly tossed her behind him.
Among all Blood Demon Arts, Muzan found the Infinity Castle most invaluable. Not only did it provide him an impenetrable fortress, but it also enabled him to rapidly summon his Upper Moons at will.
As long as Muzan remained inside, theoretically, no Demon Slayer could ever find him. The Infinity Castle was a space utterly disconnected from the human world—unless Muzan himself invited outsiders in, humans could never reach it.
"Lord Muzan mentioned turning a member of the Demon Slayer Corps into a demon recently. To avoid another incident like those two uncontrollable demons, he brought that individual here to keep him under close watch."
His gaze shifted slightly, examining Emiya's visibly strained breathing, eyes filled with undisguised curiosity.
"But... how strange. You've received Lord Muzan's blood, yet remain human."