The moment Daniel stepped out of the RV, the distant echoes of battle became clearer.
Explosions rippled across the night sky. The clash of Noble Phantasms distorted the air itself. Even without seeing it directly, one could imagine the scale of destruction unfolding beyond the castle walls.
But Daniel didn't spare it a second glance.
"Stay focused," he said calmly. "Everything happening up there is just noise."
Aura trotted beside him, her ears twitching slightly as each distant impact made the ground hum beneath their feet.
"Still feels like we're missing all the fun," she muttered.
"You'll have your share," Daniel replied. "Just not the reckless kind."
Behind them, Shalltear walked with elegant composure, as if the chaos above was nothing more than distant background music. Her crimson eyes flickered faintly as she synchronized with the vision of her familiars, guiding their route with precision.
"This way, master," she said, turning toward a concealed stone passage. "The defensive layers are thinner here. Likely overlooked due to structural redundancy."
"In other words," Aura said with a grin, "a blind spot."
"Precisely."
The group slipped into the passage.
Inside the castle, silence swallowed them whole.
The deeper they went, the more the sounds of battle faded, replaced by an oppressive stillness that pressed against the senses. Ancient walls lined the corridor, etched with faded thaumaturgical circuits. Some still pulsed faintly, remnants of defenses left unattended in the rush to deploy forces above.
Aura wrinkled her nose.
"Smells weird down here… like old magic."
"That's because it is," Shalltear replied lightly. "Layers upon layers of ritual reinforcement. This castle wasn't merely built. It was cultivated."
Daniel brushed his hand along the wall as he walked, his eyes thoughtful.
"Yggdmillennia didn't just fortify this place. They integrated it into the Greater Grail system itself."
"Meaning?" Aura asked.
"Meaning if we make a mistake," he said plainly, "this entire structure could collapse on us, or worse, trigger a backlash from the Grail."
Aura blinked once.
"Okay… maybe not reckless fun then."
They continued forward in silence.
Above ground, the battle intensified. Sparks of prana tore through the night as Servants clashed without restraint. Siegfried strained under relentless pressure while Achilles moved like a storm given form. Other battles erupted across the field, each no less violent than the last.
Yet none of them noticed that something far more dangerous had already slipped past their lines.
Back underground, Daniel and the others reached a sealed gate.
Unlike the previous corridors, this one radiated a dense, suffocating magical presence. Multiple layers of bounded fields overlapped, forming a complex defensive network that reacted subtly even to their presence.
Aura tilted her head as she examined it.
"So… we break it?"
"That would be the worst option," Daniel said immediately.
Shalltear stepped forward and placed a pale hand against the barrier. Her eyes narrowed as she studied its structure in detail.
"How intricate," she murmured. "It's not just a barrier. It reacts. Any external force would trigger a cascade."
"Exactly," Daniel said. "Brute force would announce us immediately. We're not here to fight the system. We're here to bypass it."
Aura crossed her arms.
"Then what's the plan?"
Daniel allowed himself a faint smile.
"We make it believe we belong here."
Minutes passed as Shalltear's familiars subtly adjusted the magical flow at key points along the corridor. The distortions were so small they were nearly impossible to detect, yet they spread gradually through the defensive layers like ripples across still water.
Daniel stood at the center, watching, waiting, controlling the timing down to the smallest detail.
"Now," he said quietly.
Shalltear stepped forward.
The barrier shimmered faintly.
Then it parted.
Not broken. Not destroyed. It simply ignored their existence.
Aura's eyes widened slightly.
"That's actually pretty cool."
"Basic infiltration," Daniel replied. "Against magi, subtlety is always more effective than power."
They stepped through without hesitation.
Beyond the gate, a vast underground chamber opened before them.
At its center, the Greater Grail pulsed.
Even incomplete, its presence was overwhelming. Massive magical circuits spiraled around it, feeding and restraining its power at the same time. The air itself felt distorted, heavy with unnatural energy.
Aura instinctively stepped back.
"That thing feels wrong."
"It should," Daniel said quietly.
Shalltear's lips curved into a delighted smile, her gaze fixed on the Grail.
"How beautiful… and yet so impure."
Daniel did not respond. His eyes remained locked on the Grail, calculating, assessing.
"This is it," he said. "The core of everything."
For a moment, silence filled the chamber.
Even the distant war above felt insignificant compared to the presence before them.
Then a faint ripple spread through the air.
Shalltear's expression changed instantly.
"Master."
"I felt it," Daniel said.
Aura tensed, her posture shifting as she scanned the surroundings.
"We're not alone."
From the shadows at the edge of the chamber, a figure slowly stepped forward.
"Well now," the figure said, their voice calm, touched with quiet amusement. "I had a feeling someone clever would aim for the root instead of the branches."
Daniel's eyes narrowed.
"So they did leave something behind."
The figure smiled faintly.
"Of course we did."
The air grew heavy, tension settling into every corner of the chamber.
For the first time since entering the castle, Daniel stopped moving forward.
"Looks like," he said softly, "this won't stay quiet."
Above them, the war continued to rage.
But below, in the depths of the castle, a far more decisive confrontation was about to begin.
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