The classification of monster tiers was currently determined by experts among the intelligent races, categorized according to the scale of destruction they could cause.
In terms of overall power, a 5th-Tier King-class monster and a 4th-Tier Nation-Destroyer were not dramatically different.
However, when it came to large-scale devastation—against armies, cities, entire nations—the 4th-Tier Nation-Destroyer usually possessed far greater destructive potential than a 5th-Tier King-class monster.
Research on monsters had still not reached a fully complete stage.
Even now, many scholars and biologists continued to study their properties and behaviors.
At present, the most commonly used classification system on the continent ranked monsters according to the scale of disaster they could cause.
The naming system itself already hinted at their threat level.
4th-Tier Nation-Destroyer = capable of causing a nation-level catastrophe if no Level-5 adventurers intervene.
5th-Tier Nation-Destroyer = capable of causing a nation-level catastrophe if no Level-6 adventurers intervene.
And by extension—
A 6th-Tier Continental-Sinking monster meant that if no Level-7 adventurers existed to stop it, it could trigger a disaster capable of sinking an entire landmass.
Thus, the classification relied on two factors:
The monster's intrinsic tier.
The level of adventuring parties required to prevent the disaster it could cause.
When calculated that way…
The unknown monster they had just encountered truly possessed a terrifying threat level.
Still, this classification only roughly corresponded to levels.
The difference in strength between individual adventurers could be enormous.
A Level-3 like Kanzaki Rei—could he be compared to another ordinary Level-3 adventurer?
Could a Level-6 mage like Izparut be compared with a Level-6 warrior like Fizer?
The tiering assumed average cases.
But once someone reached Level 6, there were hardly any "ordinary" people left.
Rei recalled the Level-6 professionals he had met.
Izparut.Akasei.Kumironi.Obades.Paly.
Each one of them radiated a presence that felt terrifying.
Level-6 individuals gave off a completely different impression compared to the previous tiers.
Even Messer, who had been killed by Izparut, had left Rei with an eerie and unsettling memory.
The only relatively approachable one was Aizen.
As for Fizer, Rei had only met him once and barely knew him.
"That's strange… really strange…"
Akasei frowned while examining the corpse.
"What kind of monster structure is this supposed to be? No matter how I look at it, it doesn't resemble the anatomy of a normal monster at all."
Although Akasei rarely studied theory, he was still a professional harvester—highly skilled in dissection and monster biology.
Yet the structure of this monster completely ignored the basic biological principles that monsters normally followed.
Simply put—
It didn't resemble a monster at all.
"Besides the innermost soul, there's no weakness anywhere."
"There aren't even basic organs required to sustain life."
"It's just… skin layered over more skin."
"Still, these skins are saturated with curses and corruption. They could probably be used to craft some powerful cursed items…"
Akasei carefully separated the layers of skin while preserving their functional integrity.
Each piece was sealed inside specialized curse-containment boxes, then tossed toward Rei.
"The curse concentration is extremely high."
"If someone touched it directly without preparation, it would probably be enough to drive even a Level-6 professional insane."
That sounded like quite a useful trump card.
If he ever needed to poison someone…
Rei now had a promising source of toxic materials.
After cleaning up the spoils, the group had effectively cleared the area.
Following Luvivi's sensory guidance, they chose another path leading deeper into the cavern.
Luvivi walked beside Rei and asked curiously,
"Rei, how exactly did you kill that monster earlier?"
After becoming a warrior, Rei had grown slightly taller.
He still hadn't reached full adult height, but he now stood roughly at Luvivi's chest level.
"Hmm… it's just an ability that can directly pull unstable souls out of a body."
"That monster's soul seemed a little unstable, so I figured I could try extracting it—and it worked."
Rei deliberately kept the explanation vague.
In truth, the monster's soul had not been unstable at all.
If anything, it had been sealed extremely securely within its body. Ordinary methods would never have been able to affect it.
Unfortunately for the monster—
It happened to satisfy the activation conditions for Rei's [God-Tier · Soul Sovereign].
"Oh… you really know a lot of strange abilities," Luvivi remarked.
Rei smiled.
"It's nothing special."
As they continued deeper, they encountered numerous ghost-type monsters.
Whenever Rei met one, he simply pulled out its soul.
Oh.
So the ability worked on most soul-based monsters.
Undead such as zombies and walking corpses possessed souls that did not belong to their bodies.
And pure wraith-type entities didn't even have physical bodies at all.
All of them could be killed instantly by Rei.
Looking at the monsters throughout the cave…
Almost every one of them was perfect prey for soul extraction.
BOOM—
Two enormous Corpse-Soul Aggregators collapsed heavily to the ground.
Rei extracted tens of millions of souls from their bodies.
5th-Tier Nation-Destroyer monsters.
They were grotesque behemoths formed by the fusion of tens of millions of corpses, gradually absorbing wandering souls over the years to strengthen themselves.
Along this entire path, there had actually been very little real combat.
The Cavern of Despairing Wails contained an absurd number of such monsters.
Any creature classified as a vengeful soul, undead, or spiritual entity typically possessed a soul that did not truly belong to its body.
After walking through a narrow passageway—
They reached a cliff.
Before arriving here, Luvivi had already killed a Soul-Devouring Spider from extreme range.
Below the cliff, thousands of Wandering Malice Puppets roamed the ground.
Each one possessed 6th-Tier Lord-level strength.
Rei raised a hand.
Souls began to seep out from the puppets' eyes, mouths, and noses, drifting toward his palm.
This ability was unbelievably convenient.
If future battles allowed him to choose his enemies, then as long as he targeted monsters of this type—
Victory was guaranteed.
Even 9th-Tier monsters might be instantly killed if their souls satisfied the activation conditions.
And more importantly…
Rei glanced back at the spider corpse behind them.
From now on, he wouldn't have to worry about whether enemies were truly dead.
After killing someone, he could simply extract their soul.
If the soul was gone, resurrection should be impossible.
For someone who constantly worried about enemies reviving unexpectedly, this ability was incredibly reassuring.
Luvivi poked Rei lightly.
"Hey…"
"Aren't you supposed to be refining your battle intent?"
"If you keep extracting souls like this, how are you supposed to develop it?"
Rei blinked.
"Uh…"
"I think… I forgot."
It wasn't that he had truly forgotten.
He simply kept encountering new enemies and instinctively testing whether he could extract their souls.
If extraction failed, then he would fight them properly.
But every monster so far had been extractable.
So he kept pulling souls out one after another…
Before he realized it, he had extracted a huge number of souls—yet hadn't practiced battle intent at all.
Still, familiarizing himself with a newly obtained talent was equally important.
"Haha, Rei," Akasei said, "how does this dungeon feel so far?"
Rei replied,
"Maybe my abilities just counter these monsters well, but it feels pretty easy."
Akasei raised an eyebrow, excitement shining in his eyes.
"So then—what do you say? Shall we do it?"
Rei laughed.
Of course he knew what Akasei meant.
"Brother Akasei, this dungeon still has many branching paths. And just ahead there's a hidden chamber concealed behind a puzzle."
"How about we solve the puzzle and collect the hidden treasure first?"
Akasei nodded.
"Yeah, that makes sense."
Ahead stood a massive stone gate.
A complex puzzle was embedded within the structure.
Only by solving it could the gate be opened.
In the past, the person responsible for solving dungeon puzzles had always been Izparut.
However, even Izparut was not proficient at every type of puzzle.
Some secrets were hidden far too deeply for him to perceive.
This world truly rewarded specialization.
Without the appropriate profession, accomplishing certain tasks became extremely difficult.
Rei leapt down from the cliff.
Passing through the pile of puppet corpses—
A violent gust of wind exploded outward.
It blasted the surrounding puppets away from the center.
In the middle of the ground lay a solid circular symbol.
Rei glanced up toward the cave ceiling.
The top was filled with stalactite-like rock formations.
"Quite complicated…"
Rei raised one hand and pointed upward.
「Flash of Instant Light」
CRACK—
A burst of light erupted.
Following a precise sequence, Rei shattered the hanging rocks one by one.
After the rocks fell, the hollow spaces behind them revealed dim green light shining down.
Soon afterward—
Faint green souls began flowing out from those cavities.
Rei gathered the souls.
Then, following the same order in which the rocks had been destroyed, he inserted the souls into the circular symbol at the center.
Akasei crossed his arms and nodded thoughtfully.
Hmm…
He understood absolutely nothing.
"Hey Izparut… what exactly is he doing?"
Izparut answered calmly.
"He's solving the puzzle."
"The solid symbol in the center is the ritual core of a Soul-Infusion Ceremony."
"In other words, this entire region is actually part of a ritual formation."
"To activate the ritual, specially prepared souls must be infused in a precise sequence."
Luvivi frowned.
"Pre-prepared souls? That sounds incredibly evil."
Izparut smiled.
"Well… otherwise why would this place be called the Cavern of Despairing Wails?"
RUMBLE—
As Rei completed the puzzle—
The central symbol began glowing.
The earth trembled.
The massive gate slowly rose with a deep vibrating hum.
It opened.
Having a Deciphering Scholar in the team really was convenient.
Luvivi extended her senses inside.
"There are many traps inside. But as long as you follow my instructions, none of them will trigger."
"The traps probably can't kill us, but they might destroy the treasure inside. So be careful."
So professional.
Rei couldn't help but admire it.
Working with a specialized team truly felt comfortable.
The group entered through the gate, following Luvivi's guidance carefully.
Step only on the designated tiles.
Walk across floor patterns that matched specific markings.
Pass through a wide, echoing corridor.
On both sides stood enormous statues holding different weapons.
While passing them—
You must not look into their eyes.
Keep your gaze forward.
Do not meet their stare.
Rei could sense that souls were sealed inside those statues.
At the end of the corridor stood a small chamber.
Inside rested a luxuriously decorated treasure chest.
"Even if you see a fancy treasure chest, don't touch it out of curiosity," Luvivi warned.
Rei glanced at the chest.
He could sense a soul inside it.
So it was a living trap.
Next came a seemingly solid wall.
Instead of stopping, Luvivi walked straight into it—
and passed through as if it were an illusion.
Rei had already sensed the passage on the other side.
Beyond the wall were more statues.
This time, however—
When passing them, one must stare directly into their eyes.
Only after passing them could one look away.
The entire journey proceeded smoothly.
With an Observer in the party, the dungeon's dangers were effortlessly neutralized.
"Up ahead is the treasure chamber."
"From here on, there are no more restrictions," Luvivi said.
Then she glanced toward Rei.
Rei also scanned the area before placing his hand against the wall, feeling the internal structure.
After a moment, he nodded.
"Sister Luvivi is right. I don't detect any additional restrictions either."
"However… these three doors each contain their own puzzle."
CLICK.
A crisp sound echoed.
Kumironi smiled gently.
"Akasei, please don't touch things randomly. The puzzles haven't been solved yet."
Akasei rubbed his hand.
I only touched the door once…
Rei was practically leaning against the door and nobody stopped him!
"Didn't you say there were no traps?"
Kumironi smiled warmly.
"No, I'm just worried you might break the door."
Oh.
So she wasn't worried about him.
She was worried about the door.
"Sister Luvivi, can you sense what's behind the doors?"
Luvivi shook her head.
"No. The barrier here is stronger than the one outside. It completely blocks all perception."
Oh.
Luvivi couldn't see through it.
But Rei could.
「Final Perception」 allowed him to observe the contents behind the doors.
Rei traced the patterns carved into the door.
The markings translated into Ancient Ansu Cipher Script.
The meaning written there was:
The Gate of Living Souls.
As for how to open it—
His Secret-Seeking Talent had already provided the answer.
However…
The hidden object inside made Rei hesitate.
"Izparut-sensei, Brother Akasei—are you confident you can deal with a 6th-Tier Continental-Sinking monster?"
"I might not be able to counter this one."
Inside the door was another Continental-Sinking monster.
Rei knew this through his Secret-Seeking ability.
Yet even he couldn't pinpoint the monster's exact position through direct perception.
This 6th-Tier Cavern of Despairing Wails contained an unbelievable number of high-quality monsters.
According to the theory that a dungeon was merely part of a greater nest, this dungeon must lie deep within a very high-tier nest system.
Still—
All of these Continental-Sinking monsters seemed to share one trait.
They were sealed.
Unable to move freely.
"Another 6th-Tier Continental-Sinking monster?" Akasei sounded slightly surprised.
Even for them, that wasn't an everyday occurrence.
"Perfect!"
Akasei smashed his fists together.
"Izparut—looks like it's finally our turn!"
Kumironi sighed while rubbing her forehead.
"Please try to show some restraint."
Akasei laughed.
"If it can sink continents, asking for restraint is a bit unreasonable, don't you think?"
"I still believe most of the destruction you cause is unnecessary."
"Kumironi, you're not a warrior—you wouldn't understand."
"The destruction that happens in battle… that's part of the romance of fighting."
Kumironi sighed again.
"I'd rather not understand."
"Let's not rush. Let Rei solve the other two doors first."
Rei nodded.
And honestly—
Even if they wanted to open the door immediately, he wouldn't allow it until the other puzzles were solved.
The second door revealed its contents through Rei's perception, but he couldn't immediately identify what it was.
By deciphering the riddle on the door, he discovered its title:
The Gate of Inheritance.
The origin of evil.The sovereign of resentment.The one who twists and stitches souls.The inheritor of the master of the evil nest.
The inheritance of a Nest Lord?
Such a thing actually existed?
Inside lay a ritual array, along with some unknown hidden object.
Finally—
The third door.
Inside were:
Soul-based spell techniques
Formulas for brewing potions using souls
Recipes for forging equipment with souls
Enchantment methods powered by souls
In short—
It contained a vast collection of methods for manipulating souls, along with several finished potions and pieces of equipment.