The damp air of the subterranean passage was heavy, thick with the scent of stagnant moisture, ancient stone dust, and the faint, metallic twang of old iron. High above, the roots of the world groaned beneath the city's weight, filtering a steady, rhythmic drip of water into the dark gutters.
Liana paused at the mouth of the archway, her fingers lightly brushing the cold obsidian wall. "To enter this place, I need to ask permission from my royal guards. Only then will they allow us through."
Akio wiped a smear of soot from his cheek, peering down the gloom of the unlit hall. "Hey... I think we should just go in secretly."
Daichi stood motionless, his sharp eyes tracking the strange, faintly glowing runes carved along the colossal doorframes ahead. "Hmm. Right now, I recall hearing rumors about those doors. They are far too mysterious to approach carelessly."
"Yeah," Liana admitted, her voice dropping to a cautious whisper that echoed against the damp vault. "I am too curious about it as well."
Akio leaned his back against the stone, crossing his arms as his brow furrowed. "Hmm, is that so? But for now, I still don't understand... how is Daichi going to learn a magic that will reveal the entity that harmed him?"
Daichi turned, his dark eyes locking onto Akio with quiet intensity. "You think it will only reveal my memories? No. It will reveal not only my memory, but also everything that happened around those memories. It will be like traveling through time to go back."
Liana gasped softly, her hand moving to her chest where her heart hammered against her ribs. "Oh... that is a very good idea. If you and Kairo faced that killer together, you will be able to unravel it. But the thing is..."
"Yeah," Akio chimed in, stepping closer. "Didn't our official investigation team already search through both of your memories?"
Daichi looked down at his own gloved hands, his knuckles tightening until the leather creaked. "Yeah... I think they did. Uhh... maybe it's just a complete waste of time going through all of this. But still... I am just too curious about what really happened to me."
Akio's eyes lit up with a mixture of dread and fascination. "Hey... can we see your memory as well?"
Liana shuddered, stepping back into the shadows of the pillar. "Sorry, but... I am too scared to see that monster. What if he turns out to be way too terrifying? I'm... I'm just too scared."
"Don't worry, Liana," Daichi said, his voice dropping into a calm, reassuring rhythm. "If things get way too dark, I will cast an auxiliary spell. It will filter the vision into a narrative form—explaining the situation conceptually while suppressing the graphic horrors."
Ten feet below the stone grating of the elevated walkway, suspended in the cool, silent shadow of the drainage rafters, Kairo clung to the damp iron beams.
Wearing his dark hoodie pulled tight over his head, his breathing was completely silent, his amber eyes tracking every movement of the three figures above as he eavesdropped on their every word.
Hmm... Kairo thought, his jaw clenching as the cold drip of water splashed against his neck. So if I follow them, I will discover things I would never be able to find out otherwise? Secrets of this kingdom lie down here... secrets even my father forbade me from seeking.
Before he could shift his footing, a sharp, piercing chill burst behind his temples. A translucent, deep-crimson pulse rippled directly across his vision, accompanied by a cold, synthetic chime that vibrated in the marrow of his bones.
[ SYSTEM WARNING ]
Do NOT allow the spell to reconstruct the unsealed memory block.
Direct cognitive observation of the core event will induce permanent PSYCHOTIC BREAK / INSANITY.
Kairo's breath caught in his throat, a cold sweat instantly breaking out across his forehead.
"Insane...?" Kairo whispered under his breath, his eyes wide in the gloom. "Oh no... I think I need to warn Daichi right now. Thank you so much, System, for warning me..."
He gripped the damp iron beam tighter, his chest aching as a horrific realization settled into his mind.
...But what exactly happened to me that is so vile, it would cause the System itself to warn me of insanity?
The oppressive silence of the deep subterranean corridors weighed on them like lead. For hours, their boots had clicked rhythmically against the slick obsidian flags, descending deeper into the belly of the City of Harmony than any civilian was ever meant to tread. The air down here was thick and ancient—smelling of damp mineral dust, copper rust, and the faint, bitter tang of old sulfur. Thanks to the yellowed parchment map Liana's ancestors had drafted centuries ago, they had navigated the winding labyrinth toward the library without triggering a single alarm rune.
Trailing ten paces behind in the gloom, draped in his dark hood, Kairo felt the ambient mana press against his skin like cold water.
Woah... Kairo thought, his pulse hammering against his ribs as his senses expanded outward through the heavy rock. I didn't know the Land of Harmony hid things like this. How massive is this place? Through his innate mana sensitivity, he could feel the hollow echo of vast, sealed chambers stretching even further below them—a secondary network of buried bunkers waiting in the dark. My magic can sense it clearly... but I can't dwell on that right now. I have to warn Daichi before he casts that spell.
Ahead, the narrow corridor opened into a high-arched rotunda illuminated by the cold, blue flicker of mage-lights. Two heavily armored royal sentinels stood at the base of a massive pair of bronze-bound doors, their halberds crossing with a sharp, metallic ring that echoed down the hall.
Liana smoothed her tunic, stepping forward into the light. "Hey there... I am Liana, daughter of—"
"I know who you are, Lady Liana," the lead guard cut her off, his deep voice muffled behind a steel visor. His sharp gaze swept past her, narrowing as he counted the shadows. "But what are the four of you doing down in a restricted sector?"
Liana blinked, her brow furrowing. "Four...?"
A soft rustle of cloth sounded from the darkness behind Daichi. Kairo stepped out from the shadow of a stone pillar, pulling down his hood with a faint, apologetic smile.
"Yeah," Kairo said quietly, his voice raspy. "It's me. Kairo."
Akio, Liana, and Daichi spun around, their eyes wide with utter shock.
"Kairo?!" Akio blurted out, stepping forward before throwing his arms around his friend in an unceremonious, tight hug. "What the hell are you doing here?!"
Daichi rushed over, gripping Kairo's shoulder with a hand that trembled slightly. "We thought you were still unconscious in the medical pavilion! They said you were critically injured—your condition was classified as top secret!"
Kairo rubbed the back of his neck, looking down with a dry chuckle. "Sorry... I know I'm supposed to be resting, but I was getting bored lying there. While I was walking around, I happened to eavesdrop on you guys. Curiosity got the better of me, so I followed you all the way down."
Liana stared at him in disbelief, looking back toward the long, dark tunnel they had just spent hours navigating. "But... how were you able to bypass the boundary warding, Kairo? That requires high-tier evasion magic..."
The lead guard stepped forward, his heavy steel boots crunching on the stone floor. "Listen to me, kids. This area is extremely dangerous. What lies behind these doors is a top-secret facility—something only high-ranking guards are permitted to know about. Under normal circumstances, I wouldn't even let you stand in this foyer."
The second guard adjusted his heavy polearm, his eyes lingering on Kairo's pale face. "Even though you are a Prince, Your Highness, the kingdom is under an absolute lockdown right now. So, state your business. What do you kids actually want here?"
Daichi took a step forward, adjusting his dark cuffs, his posture instantly shifting into that of a calm, studious scholar. "I just need to access some historical texts. Because of the lockdown, I can't return to the upper academy archives to study, and I need to consult specific records."
The second guard let out a heavy sigh through his iron visor, the sound echoing hollowly. "Yeah, we understand... but today, almost the entire garrison has been deployed to the northern gates for the battlefield line. It's quiet down here, but if something goes wrong... it's far too dangerous."
The second guard shifted his weight, his heavy steel sabatons grinding against the obsidian floor with a sharp, echoing scrape. He looked at the four teenagers, his visor lingering on Prince Kairo's pale face before turning back to the massive, rune-encrusted bronze doors.
"Alright," the lead sentinel said, his voice deep and muffled behind his iron helm. He unclipped a heavy, ringed key wrought from black iron from his belt. "Under strict supervision. You stay in the outer vestibule of the archive—not a single step toward the lower iron cells. If a single alarm ward trips, I'm dragging all four of you straight to General Leonhart."
Liana let out a quiet breath of relief, her hand slipping away from her tunic. "Thank you, captain. We'll abide by the protocol."
The guard pressed the heavy black key into a recessed slot beside the archway. A sharp, high-pitched hum of unsealing mana resonated through the subterranean corridor, vibrating in the soles of their boots. The ancient bronze doors groaned as hidden counterweights shifted within the stone, parting slowly to reveal a vast, cavernous hall flooded with the pale, ethereal glow of suspended blue mage-fire.
The air that washed out from the archive was freezing, stale, and dense with the dry smell of ancient vellum, decaying leather bindings, and preserved ink. Towering bookshelves wrought from petrified ironwood stretched up into the shadow of the vaulted ceiling, stacked fifty feet high with leather-bound codices and yellowed scrolls that had not seen sunlight in centuries.
"Stay close," the lead guard instructed, his iron-clad hand resting loosely on the pommel of his broadsword as he stepped into the vault first. His heavy footsteps echoed down the central aisle like iron hammers on stone. "You have thirty minutes to consult your texts before we seal the outer ward again."
Akio looked up at the towering shelves, whistling softly under his breath. "Man... it feels like walking inside the stomach of an ancient leviathan. It's freezing down here."
Daichi didn't waste a second. His sharp eyes immediately began scanning the categorization runes carved into the sides of the ironwood cases, his boots making almost no sound against the dust-dusted flagstones. "The historical registries from two hundred years ago should be located in the third alcove on the right... near the restricted temporal records."
Kairo walked slowly behind them, his dark hood pulled low over his forehead. He kept his eyes fixed on the back of Daichi's neck. The ambient cold in the room seeped through his linen tunic, but it was nothing compared to the icy dread twisting in his stomach.
Every step deeper into the library brought a faint, rhythmic throbbing to Kairo's chest—a subtle resonance from the devil's mark beneath his collarbone.
He's looking for the memory restoration texts, Kairo thought, his heart hammering against his ribs in the quiet vault. He's going to find the auxiliary spell... but the moment he tries to unlock what happened to us, the System said it will shatter his mind.
As Daichi reached out a gloved hand toward a thick, leather-bound folio titled Chronicles of the Unnamed Era, Kairo stepped forward and grabbed his wrist, his grip surprisingly firm despite his pale appearance.
Daichi paused, turning his dark eyes toward Kairo in mild surprise. "Kairo? What is it?