Sand Subsidence.
It referred to the phenomenon where the Sand Devourer used its massive body to collapse the ground from below.
In Ark, sand subsidence was deemed overwhelming, classified more as a disaster than a combat scenario, and the standard tactical manual emphasized evasion over confrontation.
Which, honestly, made perfect sense.
The Sand Devourer, under normal circumstances, wasn't something regular soldiers could handle.
Regardless, the important point was this—even Ark considers Sand Subsidence a natural disaster.
And the same went for the beasts now closing in on Ark.
KUGUGUGUGUGU────!!!!
The hollow paths I carved underground began collapsing in succession, triggering 'Sand Collapse' along every trail I had traversed.
KWAARRRRRRRRRNG────!!!!
The ceiling caved in.
To me, it was as if the sky itself were falling.
["Uwah! Are you sure this is safe?!"]
Esther screamed.
That's how catastrophic this unfolding disaster truly was.
"It'll be fine."
["You say that, but it kinda sounded like you just got a mouthful of dirt?"]
"It's fi—pffft!"
["..."]
Ignoring Esther's look that clearly asked "What kind of guy even are you?", I watched the events unfold.
[KAK, KAAAK....]
[KEHEHEK!]
These were monsters with incredibly tough life forces—just burying them underground wouldn't kill them instantly.
But it was only a matter of time.
Even monsters, once buried alive, had few means of escape.
'Can't end it here.'
Sllllk─
Janus' bone tentacles began extending outward in all directions, reaching toward the helpless monsters buried beneath the earth.
STAB! STABSTAB!
The number of bone tentacles kept increasing.
Janus looked ready to devour every last buried beast and monster.
SSSSSS──!
The blood and flesh of beasts and monsters fed Janus' power.
In other words, the exhaustion from causing the 'Sand Collapse' was now being undone—Janus was recovering.
[GEEET!]
Janus let out a cry of joy, having feasted to his heart's content.
Seemed like he was full.
"Alright then, let's go again."
[GEEGEEET!]
From this point on, it was rinse and repeat.
Together with Janus, I roamed through the earth again, creating hollow spaces underground.
['Earth Dive' has been activated.]
Bigger. Wider.
Janus burrowed with a smooth, unrelenting motion, as if swimming through water.
And once an even larger chamber than before was carved out, Janus finally completed his task.
['Sand Collapse' has been activated.]
Once again, the world crumbled.
This time, the affected area was vastly broader and more expansive than before.
KUGUGUGUGUGU─────!!!!
It was time to hunt again.
* * *
After a long journey, even though she had returned to Ark, Isabel couldn't fall asleep easily.
It wasn't because Ark was in a state of war.
It was just... something was bothering her.
"Mmm…"
After tossing and turning for a while, Isabel finally got up from bed.
Given how exhausted she was, it wouldn't have been strange for her to collapse on the spot, but for some reason, sleep wouldn't come.
"...Ugh, whatever."
She sprang out of bed and left her room.
"Young Lady?"
The servants, clearly flustered, tried to stop her, but Isabel continued walking unfazed.
"Move. I have somewhere to go."
"Where are you going at a time like this? It's dangerous."
"Do you really think there's anything that can endanger me?"
"But still…"
The servant couldn't respond.
There was no way anyone could stop the young lady at a time like this.
"I'll handle it myself. Got it?"
Without a single guard, Isabel left the mansion and headed straight for the front lines at the Red Line.
Somehow, she had a feeling that something she needed to see was out there.
"Hm…"
Her pace was neither hurried nor slow. Eventually, Turncoat Rook naturally fell into step beside her.
"You're back, Commander."
"Yeah. Been doing alright? How'd the job I gave you go?"
"More or less handled."
"'More or less'? You were supposed to do it right."
Isabel grumbled.
She had nearly died struggling to make it back alive, yet her subordinate was being half-assed about his orders…
"Anyway, what about Crux and Nameless?"
"Proceeding as planned."
"That so? Good."
Even without Esther, their plan was steadily taking shape.
Still, Isabel couldn't shake a strange feeling.
"What's wrong?"
"...Nothing. It's fine."
Isabel continued toward the front.
Normally, a few soldiers might've saluted her in passing, recognizing who she was, but right now, Ark's front lines had no such luxury.
BOOOOM───!
KWOOUUUNG!!!
Explosions and monstrous howls rang out constantly.
It was practically routine during each Wave in Ark—commonplace, even—but that didn't make it any less grim.
This was war.
A war of death and killing.
"Intercept the flying beasts first!"
"Target the flying beasts!"
At the shout of commands, Ark's firepower surged into the sky.
Flying beasts were among the greatest threats to Ark's defense lines, so they couldn't afford to hold back.
Isabel slipped onto the gate wall like a phantom and scanned the battlefield.
"Hmm…"
Some soldiers cast glances at her as if they'd seen a ghost, but that was as far as it went.
The frontline was far too tense for them to give her any more attention.
"What are you staring at?"
"Shh. Be quiet."
Isabel silently gazed beyond the front.
Compared to the overwhelming number of ground troops, the sky forces seemed slightly lacking.
It couldn't be coincidence.
She already knew who was involved in this war.
"Hm…"
Isabel had a rough idea of what Carl Marcus had been doing outside of Ark.
She knew—at least to a certain extent—just how hard he had fought and how much blood he had shed to protect Ark.
But this time, something was different.
Usually, when Carl Marcus engaged in battle, it was far beyond Ark's range of sight. But what was happening now could be seen even from Ark.
"That's…"
"What is it?"
"Just watch."
Sand Subsidence Phenomenon.
It was happening beyond Ark's front line.
"Huh?"
Only then did Rook narrow his eyes, sensing something was off.
"What is that?"
"Sand Subsidence."
"No... I know that. But why is it happening there?"
According to common knowledge, the Sand Devourer didn't appear during Waves.
If it did, Ark would have been annihilated long ago. Fortunately, that had never happened.
But… what in the world was going on out there?
"Carl Marcus."
"What about him?"
"Just know that."
Isabel waved her hand dismissively, uninterested in dealing with Rook right now.
She wanted to focus more on the front line.
"He's doing well."
"Who? Carl Marcus?"
"Yeah."
Isabel turned away.
"Let's head back."
"Already? After coming all this way?"
"I've seen what I needed to see."
Rook couldn't understand what she meant, but he nodded anyway.
He already had enough on his mind without trying to figure Isabel out.
'Probably nothing serious…'
Rook shook his head and glanced at the front.
'So, Carl Marcus is out there?'
It struck him again—how quickly Carl Marcus was changing day by day.
At this rate, he could easily become a serious threat to the Shadow Corps.
'…No. He already is.'
Rook had no idea what had happened between Isabel and Carl Marcus, but he wasn't about to let his guard down.
He turned away.
『"Submit…"』
And ignored the whisper that echoed by his ear.
*
Just how many monsters and beasts had I buried alive?
[You have slain Grade-8 Beast Type: Skull Hound.]
[Damage to Grade-8 Beast Type: Skull Hound increases by 0.05%.]
[You have slain Grade-4 Beast Type: Black-furred Tyranno.]
[Damage to Grade-4 Beast Type: Black-furred Tyranno increases by 0.05%.]
[You have slain Grade-8 Crag Monster: Granite Golem.]
[Damage to Grade-8 Crag Monster: Granite Golem increases by 0.05%.]
.
.
.
[You have slain Grade-5 Primate Type: Demon-Arm Chimpanzee.]
[Damage to Grade-5 Primate Type: Demon-Arm Chimpanzee increases by 0.05%.]
With the flurry of system messages ringing in my head, I retracted the bone tentacles I'd scattered throughout the area.
Janus had just finished his feast.
'Alright then... let's get out of here.'
I extended Janus' retrieved tentacles once more.
['Earth Dive' has been activated.]
SSSSSH──!
I was deep underground, but emerging took barely a second.
That's how broken Janus' new 'Earth Dive' ability really was.
FWOOOSH!
In an instant, I surfaced and scanned the surroundings.
'Hm.'
Just as I expected.
The land where I emerged was utterly devastated.
What had once been flat plains had collapsed into pits, and half-submerged beasts and monsters thrashed to free themselves.
[KAAK! KAAAK…]
[KYEEK, KYEGYEG!]
Naturally, the number of monsters visible on the front had dropped significantly compared to the beginning.
Sand Collapse had hit home.
'It really is insanely effective against ground-based monsters.'
Of course, some high-tier monsters either escaped the collapse or dodged it beforehand.
But the rest weren't so lucky.
[KIEEE…]
[GAGAGAK…]
Even so, the sheer number of enemies left was still mind-numbing.
But I'd established control in the early stages—now all I had to do was continue the hunt.
'Let's keep going.'
I opened my rift space.
It was time to retrieve the now-cooled NOA-31 Anti-Behemoth Gatling Gun and the CRN-842 Hemp Rocket Launcher.
KUUUUUNG───!
The NOA-31 emerged from the rift and slammed its hulking frame onto the ground.
Grabbing the NOA-31's handle, I pulled the trigger again.
BOOMBOOMBOOMBOOMBOOM────!!!
With a burst of roaring flame, a blazing flash tore through the oncoming beasts, shredding their bodies like rags.
I didn't stop there.
CLACK─
I pulled out the CRN-842 Hemp Rocket Launcher, gripped the trigger with my left hand, and locked it into place with ether.
This way, I could dual-wield heavy weapons.
'Alright then…'
Crimson flames burst from both my hands.