The following morning was eerily calm.
From the outside, Seiki Academy moved as if nothing unusual had happened. Students gathered for lessons, sparring sessions echoed in the courtyards, and faculty members roamed the halls with polite smiles. But for Kaito, Hina, and Riku, the silence felt heavier than ever.
They had barely slept after the encounter with Rei in the Undercroft tunnels. His words echoed in Kaito's mind like a lingering curse.
"The Void will eat you alive before you ever understand it."
What did he mean? How did he know?
After morning drills, the trio slipped away from the crowd, retreating to an isolated corner of the library. It was one of the few quiet places left—a towering chamber filled with bookshelves that stretched upward like the ribs of some ancient beast.
Riku scanned the shelves with a focused look. "If Rei knows about the Void, his history might not be public. But the Academy keeps record scrolls for every student who's ever enrolled—sometimes even for families connected to Seiki anomalies."
Hina raised an eyebrow. "So you're saying there might be… a file on him?"
"And maybe," Riku said quietly, "there's a file on the Void itself."
Kaito stayed silent, his fingers brushing along the spines of dusty tomes. He could feel it—the faint, almost imperceptible pull toward something hidden deeper in the library.
Eventually, Riku's threads triggered a faint clicking sound near the back wall. A section of the bookshelf shifted inward, revealing a narrow spiral staircase descending below.
"Figures," Hina muttered. "Another creepy hidden staircase."
Riku smirked faintly. "It's the Academy. Everything important is buried."
The three descended carefully.
The Hidden Archive
The staircase ended in a circular room carved entirely from black stone. Dim lanterns flickered to life automatically, revealing rows of scrolls bound in silver threads. At the center of the room was a single pedestal holding an ancient ledger, its pages brittle and yellowed.
Riku approached first, his threads carefully peeling back the cover. "This is a Kurai Archive," he said softly. "Records of forbidden Seiki and the vows tied to them."
Hina looked around uneasily. "So this is where they keep the dirty secrets."
Kaito's gaze locked on the ledger. Something about it called to him.
As Riku flipped through the brittle pages, they saw drawings of strange Seiki techniques—ones unlike anything taught at the Academy. Jagged shapes, swirling voids, and tendrils of shadow etched into the paper.
And then they saw the heading:
Kurai no Yakusoku – The Dark Vows
Riku read aloud, his usually calm voice tinged with unease.
"Dark Vows are forged from desperation. Unlike ordinary Yakusoku, which limit and stabilize Seiki, Dark Vows amplify power at the cost of consuming the user's essence. Those marked by the Void are chosen, not born. The hunger cannot be cured—only delayed."
Kaito froze. "Chosen… not born?"
Hina glanced at him. "Kaito… this is about you."
Riku turned the page.
"In every generation, one or two are marked by the Kurai—an ancient fragment of Seiki energy from before the Academy's founding. They are known as Bearers. Their vows, if broken, unleash cataclysmic destruction."
The room felt colder. Kaito's chest tightened, the Void inside him swirling in uneasy agreement.
Hina clenched her fists. "So… you're saying the Academy knew? They knew about this and still let you in?"
Before anyone could answer, a faint clap echoed from the shadows.
"Impressive. You found it faster than I expected."
The trio spun around.
Standing near the entrance was Rei.
But this time, he wasn't smirking. His expression was calm, almost… sad.
"You weren't supposed to read this yet," Rei said quietly. "The more you dig, the faster the Void will awaken."
Kaito stepped forward. "Enough riddles, Rei! What is this? Why do you know so much?"
Rei's blue eyes locked onto his. "Because I'm like you."
Silence.
Riku's eyes narrowed. "You're saying… you're a Bearer too?"
Rei nodded slowly. "The Academy doesn't just train students. It collects us. Studies us. We're pawns in something far bigger than you realize."
Hina's aura flared in anger. "So all those missing students—"
"They're in the Undercroft," Rei interrupted, voice flat. "They broke. Their vows collapsed, and the Academy sealed them away before they could destroy everything."
Kaito felt his knees weaken. "No… you're lying."
"I wish I was," Rei said. "I barely survived my first collapse. I learned to control it, but only by accepting the truth—there's no escaping the Void. There's only delaying it."
Before they could ask more, a low rumble shook the room. The lanterns flickered violently, and the walls themselves began to shift.
Riku stiffened. "It's a trap. The archive is reacting to our presence."
The stone floor beneath them opened into jagged gaps, revealing a massive puzzle-like labyrinth forming around them. Spiked barriers rose from the ground, and chains of glowing Seiki energy began constricting the exits.
Rei's expression hardened. "You triggered the Archive Trial. It won't let us leave without passing."
"Passing?" Hina shouted, dodging a falling slab of stone. "What do you mean passing?!"
"The Archive tests your vow," Rei said, his voice calm despite the chaos. "If your vow is weak, it will crush you. If it's strong, it will show you the path forward."
The floor split into multiple platforms hovering over a dark void. Strange glyphs floated in the air like shifting keys.
Riku analyzed it instantly. "We have to activate the glyphs in the correct order or the platforms will collapse."
"Of course it's a puzzle," Hina groaned, already punching aside a falling debris spike.
Rei stepped lightly onto one of the floating platforms. "Follow me. I've done this once before."
Kaito hesitated. "Why are you helping us now?"
Rei glanced over his shoulder. "Because if you die here, no one will stop what's coming."
The Archive Trial
They moved quickly, leaping from platform to platform as the labyrinth shifted around them. The glyphs emitted faint pulses of energy—each one tied to a concept: Sacrifice. Hunger. Restraint. Resolve.
"It's reading us," Riku muttered. "Measuring our vows."
Hina touched a glyph marked Resolve, and the platform beneath her stabilized. "Got it! Pick the ones that match our promises!"
But when Kaito stepped toward a glyph labeled Hunger, it pulsed violently. The Void inside him reacted instantly, tendrils threatening to burst out.
Rei's voice cut through sharply. "Don't touch that one. It'll accelerate your collapse."
Instead, Kaito chose Sacrifice, feeling his vow resonate faintly. The platform steadied, and the path extended further.
Bit by bit, they worked together—Riku calculating the sequences, Hina providing raw power to clear collapsing paths, Rei guiding them through the most dangerous traps.
But halfway through, the Trial revealed its true danger.
A massive manifestation of Seiki energy—a writhing creature made of glyphs and shadows—rose from the void below. It screeched, sending waves of destabilizing force across the platforms.
"It's a Guardian," Rei said grimly. "It feeds on fear and hesitation. If your vow wavers, it will devour you."
The creature lunged.
Hina leapt first, fists blazing, striking it hard enough to stagger it—but the shadow reformed instantly, retaliating with tendrils that almost knocked her into the void.
Riku's threads lashed out, binding part of the creature to slow it down. "Kaito! Now!"
Kaito closed his eyes, focusing on his vow. The Void roared within, eager to consume—but he held onto his promise, his anchor.
Then he released a controlled surge of Void tendrils, striking the Guardian's core glyph. The shadowy mass shrieked and dissolved into fragments of energy, stabilizing the labyrinth again.
For a moment, there was silence.
Then the final path opened, leading to a glowing door at the center of the labyrinth.
The Revelation Room
They stepped through the door and into a circular chamber. At its center floated a massive black crystal pulsing with faint light. Around it were dozens of empty chains—bindings that had long since been broken.
Inscribed on the floor were the words:
"To bear the Void is to bear the world's oldest sin."
Rei approached the crystal slowly. "This… is a fragment of the original Kurai Seiki. The Academy keeps it here to study us."
Kaito stared at it, feeling an overwhelming connection—like the crystal was alive, whispering directly into his soul.
"Kaito Renge…"
The voice came again—faint, echoing inside his mind.
"You are next."
The crystal flared with a sudden, blinding light.
Before anyone could react, the room shifted violently, pulling Kaito toward the crystal as the Void inside him fully awakened for a split second.
Hina screamed his name.
And then—
Everything went black.