The deeper we went, the quieter the slave house became.
Not silent.
Just… wrong.
The sounds of shouting guards and distant alarms gradually faded behind us until only the low hum of mana lamps remained.
The massive underground corridors stretched endlessly ahead, twisting through reinforced stone hallways lined with black metal supports and glowing formation markings.
Honestly, this place was absurdly huge.
“You’d think people kidnapping and selling slaves would settle for a normal dungeon,” I muttered while stepping over broken stone from earlier fights.
Lyra walked a few steps ahead of me, black eyes scanning every corner with calm alertness.
“Rich nobles enjoy excess.”
“Apparently.”
The walls had changed at some point.
The rough prison stone was gone now, replaced by smooth dark metal etched with faint runes that pulsed softly with mana.
Pipes lined parts of the ceiling, carrying glowing blue liquid deeper underground.
Security formations too.
A lot of them.
Enough to make it obvious this wasn’t part of the normal prison sectors anymore.
My eyes narrowed slightly.
Then I remembered.
Ah.
Right.
The hidden laboratory.
The novel mentioned it briefly during one of the later arcs.
Slaves who displayed unusual talent or mana compatibility weren’t always sold immediately.
Some were brought here instead.
Experimentation.
Research.
Human testing.
Children included.
A cold feeling settled in my stomach.
Thankfully, I never used mana before getting captured.
Otherwise…
Yeah.
That would’ve ended badly.
Still, something bothered me.
‘Wait.’
[Yes, Host?]
‘Shouldn’t they have sensed my rank anyway?’
The system answered immediately.
[The System provides passive concealment functions for the Host.]
I blinked.
‘…Excuse me?’
[Your mana fluctuations, rank signature, and abnormal affinity presence are automatically suppressed unless manually disabled.]
I stared ahead for a moment.
‘That is unbelievably convenient.’
[Thank you.]
‘Why do you sound proud?’
[Because I am extremely efficient.]
I snorted quietly.
Lyra glanced back immediately.
“What?”
“Nothing.”
“You keep randomly smiling at empty air.”
“Okay first of all, rude.”
“You’re losing sanity.”
“I’m developing character depth.”
“You’re developing brain damage.”
“…You know, emotionally, that really hurt.”
She ignored me completely and kept walking.
Honestly unfair.
A faint scream echoed through the corridor ahead.
Both of us stopped instantly.
The scream cut off abruptly.
Silence followed.
Not normal silence either.
Heavy silence.
The kind that made instincts crawl unpleasantly beneath your skin.
Lyra’s expression darkened slightly.
Mine probably did too.
We moved faster after that.
The corridor eventually narrowed before opening into a massive reinforced section guarded by thick metal doors covered in suppression runes.
Unlike the rest of the prison, this area looked almost military.
And outside the entrance—
Bodies.
Three guards lay dead near the doorway with clean wounds across their throats.
Fresh.
Lyra crouched beside one briefly before standing again.
“Not ours,” she said quietly.
“Internal cleanup?”
“Probably.”
Well.
That definitely wasn’t ominous.
The massive doors stood partially open already, pale blue light spilling outward through the narrow gap.
And beneath it—
Voices.
I exchanged a glance with Lyra before pushing the entrance open carefully.
Then we stepped inside.
And immediately—
Yeah.
Nope.
This place needed to burn.
The hidden laboratory stretched far underground beneath the slave house, larger than I expected.
Rows of containment chambers lined the walls beside massive glass cylinders connected to humming machines through thick tubes carrying black liquid.
Children.
There were children everywhere.
Some restrained on operating tables.
Some suspended inside glass containers filled halfway with dark fluid.
Some unconscious while tubes pumped black substances directly into their veins.
Others twitched violently against restraints while researchers calmly monitored glowing screens nearby.
A little boy screamed weakly as dark veins spread beneath his skin.
One of the researchers adjusted a tube connected to his arm without even looking at him properly.
“Mana rejection rate is rising.”
“Increase the dosage.”
“But his body won’t—”
“Then stabilize it.”
The child screamed louder.
My jaw tightened instantly.
Okay.
Yeah.
Now I really wanted to kill people.
The laboratory smelled awful.
Blood.
Chemicals.
Burned mana residue.
Something rotten underneath all of it.
One girl floated motionlessly inside a containment tank while black liquid swirled slowly around her body through attached tubes.
She couldn’t have been older than nine.
Another child simply stared blankly upward from an operating table, eyes hollow and unfocused.
No reactions.
No resistance.
Just emptiness.
Something cold settled heavily in my chest.
Beside me, Lyra suddenly stopped moving completely.
I looked toward her.
And paused.
For the first time since meeting her—
She looked angry.
Not annoyed.
Not irritated.
Actually angry.
Mana trembled faintly around her fingers while her black eyes locked onto the researchers across the room with open disgust.
Honestly?
It suited her dangerously well.
I smiled slightly.
‘Guess I’m not the only one who wants to kill these bastards.’
[Host.]
‘What?’
[You are staring again.]
‘Can you blame me?’
[Yes.]
Before I could continue mentally bullying the system, another scream echoed across the laboratory.
A young girl convulsed violently against restraints while black liquid pulsed through the tubes connected to her body.
One researcher sighed irritably.
“Increase suppression output.”
“She may die.”
“Then record the failure and move on.”
Move on.
Like she wasn’t even human.
Beside me, Lyra finally spoke.
“These people are disgusting.”
Her voice came out low and trembling slightly with fury.
“They’re doing this to children?”
Even whispered, the killing intent behind her words made the air feel colder.
I turned toward her slowly.
Then grinned.
“Well…” I cracked my knuckles softly.
“What do you say we teach them a lesson?”
For a second, she stared at me silently.
Then a dangerous glint entered her black eyes.
A small smirk touched her lips.
Sharp.
Beautiful.
Deadly.
Gods.
Why was that so attractive?
‘Gods, why is she so beautiful?’
[Host, snap out of it.
You are losing aura.]
‘Shut up.’
[I am serious.]
‘You literally don’t understand aura.’
[You understand that staring at dangerous women during life-threatening situations lowers survival probability.]
‘Worth it.’
[Hopeless.]
Her smirk widened slightly like she somehow knew I was internally malfunctioning.
“You read my mind,” she said quietly.
Then—
One of the researchers finally noticed us.
The man froze instantly.
“…Who are yo—”
Lyra moved first.
Fast.
Ridiculously fast.
Silver hair flashed beneath the pale laboratory lights as she crossed the room in a blur.
Her dagger sliced cleanly across the researcher’s throat before he could finish speaking.
Blood sprayed across nearby equipment.
Silence lasted exactly half a second.
Then chaos exploded.
“INTRUDERS!”
“Security!”
“Protect the specimens!”
Specimens.
Not children.
Specimens.
Yeah.
Everyone here was dying.
A guard reached toward a nearby alarm formation—
‘[Blink].’
Space folded instantly.
The world twisted sideways before I reappeared beside him.
My fist met his face hard enough to cave it inward.
CRACK.
The guard collapsed immediately.
Another researcher stumbled backward while fumbling desperately for a mana device.
Lyra’s dagger buried itself directly into his chest before he could activate it.
Honestly terrifying girl.
The laboratory erupted into complete panic after that.
Researchers screamed.
Machines blared warning alarms.
Guards rushed in from deeper sections while several scientists desperately tried protecting equipment instead of the children.
Interesting priorities.
A spear-wielding guard charged directly toward me with mana coating his weapon.
I sidestepped casually.
Grabbed his arm.
Then slammed his face through the nearest containment chamber hard enough to shatter both.
Glass exploded outward.
Black liquid spilled across the floor.
The child inside the chamber collapsed weakly into my arms.
Still breathing.
Barely.
Dark veins crawled beneath the boy’s skin while unstable mana leaked from his body in painful bursts.
The black liquid coating him hissed faintly against the floor.
Demon extract.
The novel mentioned this too.
Some lunatic discovered diluted demon blood could strengthen mana circuits temporarily.
The side effects were usually insanity, mutation, organ failure, or death.
Minor inconveniences apparently.
A guard lunged toward me from behind.
Before I could react—
A black blur flashed past.
Lyra’s dagger pierced straight through the man’s throat.
She landed lightly nearby, silver hair swaying softly while tiny blood droplets stained her cheek and sleeve again.
Seriously.
How did she keep looking prettier after fights?
That felt illegal somehow.
[Host.]
‘I know.’
[No.
You clearly do not.]
She glanced briefly toward the unconscious child beside me.
“…Alive?”
“Barely.”
Her expression darkened further.
Then—
BOOOOOM.
The entire laboratory shook violently.
Both of us looked up immediately.
Heavy footsteps echoed from somewhere deeper underground.
Slow.
Controlled.
Powerful.
Not normal guards.
The researchers heard it too.
And immediately relaxed.
One of them pointed toward us frantically.
“Director!
They breached the laboratory!”
Director?
Well.
That sounded concerning.
A massive reinforced gate slowly opened at the far end of the room.
Cold air spilled outward from the darkness beyond.
Then a figure emerged.
Tall.
Thin.
Black robes lined with silver mana inscriptions.
Glasses.
Calm expression.
And mana pressure vastly heavier than the [E] ranker from earlier.
The moment he stepped fully into the laboratory, every remaining guard straightened instantly.
Even the researchers looked nervous around him.
Interesting.
The man’s eyes moved slowly across the ruined laboratory.
The dead guards.
The shattered containment chambers.
The freed children.
The broken equipment.
Then finally—
His gaze landed on me.
And stopped.
A strange silence settled over the room.
“…How troublesome,” the man murmured calmly.
Every instinct in my body sharpened instantly.
Danger.
Real danger.
Beside me, Lyra subtly adjusted her stance too.
Good.
So I wasn’t imagining it.
The man adjusted one of his gloves carefully while examining the destruction surrounding us.
“You destroyed years of valuable research.”
I glanced around deliberately.
“…Feels more like community service honestly.”
One of the nearby researchers looked horrified that I said that out loud.
The man in black robes studied me silently for several seconds.
Then his gaze shifted slightly toward the faint spatial distortions still lingering around the broken laboratory walls.
His eyes narrowed almost imperceptibly.
Ah.
He noticed.
Interesting.
The mana pressure in the room grew heavier.
Behind us, frightened children huddled weakly near shattered containment tanks while warning alarms screamed overhead.
And standing there beside Lyra in the middle of the ruined laboratory—
I smiled.
Because something told me this was about to become very, very violent.