The behavior of Erosion Species was, in most respects, closer to that of beasts.
Dialogue and negotiation were concepts that simply did not exist for them.
They were ravenous, as though perpetually starved — utterly devoid of anything resembling fear.
Which was why they would bellow at the sight of any human.
Why they would charge first even in situations that were obviously disadvantageous.
Why they fell for the simplest of feints without fail.
The division between Tankers and Dealers had come about for exactly that reason.
The Tanker absorbs every attack from an agitated Erosion Species.
The Dealer accumulates damage from a safe distance.
That was the most efficient method for fighting Erosion Species.
"Ugh…?! It's aggro'd again…! Watch yourselves, it is!"
"Dangerous…."
"Ugh…. Yubina! I can't land a hit! Create some distance!"
"Ngh, this thing won't let go, it won't!"
But Midir was different from every Erosion Species that had come before.
It hadn't roared once — not a single time — and it moved in silence.
Its gaze swept the surroundings in constant, unbroken vigilance.
It paid Yubina almost no attention whatsoever.
As though it already knew she couldn't deal any meaningful damage.
And that wasn't all.
Whether the gunfire coming from behind was irritating it or not —
it moved to use Yubina as a shield.
It deliberately left openings, then targeted Anje when she closed in.
It slammed its tail against the ground and sent rock fragments scattering toward the rear.
It moved as though the Tanker simply didn't exist.
Naturally, the fight against Midir spiraled into chaos.
*As expected…. Of every Erosion Species I've ever fought, this one is the most troublesome.*
Naturally, Midir was no ordinary Erosion Species.
No — if anything, it might have been the most singular creature in the world.
Because it possessed intelligence that bordered on human.
Slipping into the city in secret to prey on civilians and Valkyries.
Hiding in the ceiling, poised to ambush Promina, the Supporter.
None of it was coincidence. Every move was a conclusion it had reasoned out on its own.
Fighting this thing required abandoning every assumption I'd built up until now.
*At this rate, it's only a matter of time before we're all combat-ineffective.*
The one saving grace was the lighting drones positioned throughout the cave.
In a cave with no light at all, if Midir started slipping through shadows, we wouldn't last ten seconds.
In our current state, though… I could manage this alone.
Having reached that conclusion, I turned to look at Promina.
She was busy healing Anje and Dahlia as they took damage —
but I didn't want her wasting her abilities on something so pointless.
"Promina. Attach a few body-enhancement butterflies to me."
"Huh? Yes! Of course."
"And… I'm leaving the Commander in your care."
"L-Leila? What are you planning?"
"I'm stepping forward. Explanations later!"
I handed the Commander off to Promina and broke into a run.
Naturally, both of them looked startled by the sudden movement.
Which was a perfectly reasonable reaction.
My role was, strictly speaking, that of a gunner.
There was no reason for me to go charging into danger on my own.
But the enemy was something that defied every assumption about ordinary Erosion Species.
Even with some risk involved, this was a situation that called for me.
"Leila! What on earth are you—?!"
"Everyone, fall back! You're in my way!"
In the original story, the Rabbit Hole Squad is rendered combat-ineffective in this fight.
Promina takes a deep slash across her back from a surprise attack and loses consciousness.
Yubina and Anje sustain injuries that leave them unable to fight.
But I needed their combat strength for the plans ahead.
I passed a stunned Yubina and stepped forward.
"…Krrk."
Midir made a sound as it watched me step out alone.
I took in its appearance — a beetle-like exoskeleton, elongated limbs, a long tail.
Its height was roughly three meters. About twice mine, give or take.
Yet despite that overwhelming difference, it was wary of me.
Even as one of the strongest creatures alive, it was always afraid.
That was precisely what made it the most troublesome enemy of all.
*Well then… shall we play?*
I moved first.
I closed the distance with my Nail Gun leading the way.
The moment I entered its range, I pulled the trigger.
The nails that served as ammunition accelerated along the electromagnetic rail, breaking the sound barrier.
The force was enough to wound even the resilient body of an Erosion Species.
But it seemed just barely insufficient to breach Midir's defenses.
The nail scraped across its exoskeleton as it braced, and ricocheted away.
"Krrrrr…."
That was apparently enough to convince it to move. It lunged at me.
It had been crouching in anticipation — what a coward.
Maintaining a razor-thin margin of distance, I peppered Midir's body from every angle.
*Hmm… punching through the exoskeleton with the Nail Gun is out of the question. I'll have to aim for the gaps.*
The brief window when I emptied a magazine and swapped it out.
Midir kicked off the ground and charged straight at me.
Of course, I'd expected exactly this, so I wasn't particularly rattled.
I calmly swapped the magazine and stepped to the side.
But had it predicted which direction I'd dodge?
Midir followed my movement with an unpredictable, almost impossible shift.
Looking closely, I saw its tail had driven into the ground.
"Using your tail like that — how underhanded…!"
If I took this hit, I'd end up in two pieces.
I leapt backward as though clearing a high jump and avoided the attack.
With the reload finished, I fired electrically charged nails — thunk, thunk.
Midir swiftly deflected them with the exoskeleton on its shoulder.
Still, at this distance, the second attack shouldn't reach—
I let my guard down for just a moment, and it whipped its tail at me.
Remarkably, the tail was longer than its arms — more than long enough to connect.
"Krkrk!"
"What are you laughing about. Did you think you'd won?"
I scoffed at Midir's apparent delight.
Then I discharged electricity, magnetizing the nails I'd pre-loaded into my clothing.
In other words, I now had a dozen or so powerful magnets embedded in my outfit.
Using the electrically charged nails I'd fired in advance, I redirected my posture mid-air.
*I'll need to account for the tail.*
I narrowly avoided the attack and landed cleanly on the ground.
I immediately fired the Nail Gun again, reading its movements.
Perhaps because this was its first time fighting a Valkyrie.
Aside from the unpredictable tail attacks, Midir's movements were straightforward.
No matter how powerful an attack is, it means nothing if it can't connect.
Its inexperience in combat was plain to see.
"Kiiiiik!"
Midir let out its first real scream.
A sharp nail had found a gap in its exoskeleton and buried itself there.
Perhaps it had rarely experienced genuine pain before.
Its movements became immediately, visibly more passive.
It seemed less interested in finishing me off and more desperate to escape.
But a cornered rat will bite the cat.
While it scattered rock fragments to keep me at bay —
Midir finally noticed the existence of the lighting drones mounted on the ceiling.
The only light source illuminating a cave that would otherwise be pitch black.
It stopped targeting me and began going after the lighting drones instead.
"Everyone, get out of the cave now! Without the lights, fighting is impossible!"
"Yes! All units, retreat, they should!"
"Commander, carry me."
"Understood."
With that, the fight was no longer viable.
Its ability was to traverse shadows.
More precisely — the power to make shadows its own domain.
Which meant Midir in a lightless cave was invincible.
Until just now, it seemed not to have noticed the lighting drones.
But given this development, retreating was the correct call. I couldn't die here.
*I wasn't planning to kill it anyway. This is a perfectly convenient excuse.*
We used the window while Midir destroyed the lighting drones to rush out of the cave.
Once we made it safely outside, I turned to the Commander.
"Commander. Please contact the branch immediately. We need to request backup from headquarters. That Erosion Species just now… we absolutely cannot afford to let it escape."
"Understood."
"I think I understand what Leila meant, I do."
"Honestly, I felt it too — that it was dangerous. The sense that we can't just leave it alone…."
They didn't seem to have grasped that Midir possessed actual intelligence.
But the Rabbit Hole Squad had clearly sensed something was off.
And no wonder — an Erosion Species that used the Tanker as a shield to attack the rear.
Nothing like that had ever appeared before.
It wasn't for nothing that the original story treated it as the worst possible threat to humanity.
Well… in the original, they managed to deal with it before it fully awakened, somehow.
*That aside. It should be about time.*
While the Commander was busy contacting the branch —
I pricked my ears and focused on the sounds drifting toward us.
Several minutes had already passed since we left the cave.
If my prediction was right, it should be reaching us right about now.
And right on cue, a sound came rolling in from far away, rattling the air.
—GROOOOOOOAR!
"Ugh?!"
"That sound is…."
"Erosion Species?!"
A roar so ferocious it was hard to believe any living creature had produced it.
It rang out again and again from the distance, without pause.
Even the Commander — who rarely showed emotion — went pale.
We sprinted toward the direction of the sound.
And at a steep cliff where the mountain range stretched into view in the distance —
we arrived to find ourselves facing an uncountable mass of shadows.
"Th-that's…."
"Don't tell me all of those are…."
"You can't be serious…."
Dozens. Hundreds. Erosion Species, beyond counting.
An overwhelming number visible even from several kilometers away.
Beneath the moonlight, they were tearing through the forest, advancing toward us.
What were you even supposed to do when faced with something like that.
The Rabbit Hole Squad wore expressions of pure, hollow disbelief.
*They have no intention of letting us leave quietly.*
Obviously — this was Midir's doing.
Its purpose: to eliminate me, the one who had wounded it.
In the original story, Leila's Blue Thunder had struck a careless Midir directly.
Midir's weakness, the one thing that could pierce its shadow-traversing ability, was light.
Leila's lightning had been exactly that — a strike aimed straight at its vulnerability.
Midir had writhed in pain it had never imagined possible.
Without a moment's hesitation, it had fled the cave in a panic.
And then it unleashed every Erosion Species it had been collecting.
Each one individually wasn't particularly strong — but there were hundreds of them.
Just looking at them was enough to drain the will to fight. A truly hopeless situation.
"Something like this… what are we even supposed to do…."
"Even if backup comes, it'll take hours…."
Think.
Here we had Leila, the Rabbit Hole Squad, and the Commander.
But the Rabbit Hole Squad — all but one — were combat-ineffective.
If the Erosion Species were left unchecked, everyone in the city would die.
So what choice would the original Leila make here?
—*I'll buy you time. Commander, please — bring back reinforcements.*
That was it. A self-sacrifice worthy of a saint.
To buy time for the backup coming from headquarters.
She sent the Commander away and remained on this mountain alone.
Of course, Leila wasn't actually that strong.
A B-rank, among Valkyrie ranks that went all the way up to S.
Her unique ability: firing a moderately powerful bolt of lightning — exactly five times.
She was only treated as formidable because of Lumia's special circumstances.
Strictly speaking, she was on the weaker end of the spectrum, world-scale.
And so, Leila dies here.
In a wretched state, right before the eyes of the Commander who returns with reinforcements.
*Hah…. Finally. I've made it this far.*
My heart was pounding.
Even now my face looked like this — what expressions would they all make in the final moment?
I stepped forward, standing before the Rabbit Hole Squad and the Commander, who had lost all will to act.
"Everyone, listen to me."
*Don't be afraid.*
*I won't let any of you die.*
"I have a way."
I pressed down hard on the face that wanted to break into a wide, wide smile.
I could only hope it wasn't making some strange expression.