Inside the Cave of Obscenity – Chapter 1

Chapter One

The Day It Was Born


A [Hero] summoned from another world defeated the [Demon King] after many years.

The [Hero] returned to his world, the monsters brought forth by the [Demon King] radically decreasing in numbers.

The monsters that had once filled the world were now suddenly bundled away in the depths of forests and caves.

And so, the few remaining monsters decreased in number even more due to current adventurers and knights.

—This world, one ran by humans and demi-humans.

A world where monsters did not exist.

A world of peace.

A world where people quarreled with one another.

A world where humans and demi-humans worked together.

A world where there was no [Demon King].

A world where there was no [Hero].

A world governed by the three rulers that had traveled together with the hero.

That was this world.

[A World Saved by a Hero From Another World] — Euswara.

A garden world, thought to be created by Goddess Euswara.

A world where there were swords and magic, and where spirits, demi-humans, demons, and humans lived.

A world where in the not so far future, there would be no monsters.

—It was to be expected.

That was what everyone thought.

Humans, spirits, demi-humans, demons, the goddess—even the [Hero], they all believed that.

That is, isn’t that simply how it would be?

Monsters were brought forth by the [Demon King], who no longer existed.

In that case, there was no means of creating any more monsters…




One of the three rulers, the Magic Queen [Leticia].

Leticia supervised the northern country, [Fonteau].

Traveling together with the hero, Leticia, a mage, had defeated the demon king.

Even her allies were struck in wonder by her… using her fearful mana to subjugate the demon king, her genius had become a natural calamity1.

Her mana was tremendous, and although it didn’t reach the likes of the demon king or the hero, it was extraordinary even when compared with the elves that were skilled in magic.

Both the person herself and those around her thought as such.

The passage of time caused the demon king’s terror to fade from the person’s memories, but she had polished her beauty even further.

Even in those days she could certainly have been called a beauty.

Flowing silver hair, like long and beautiful silk. Large red eyes, with well-regulated eyebrows. Her gaze was sharp, but even that was still one of her charms.
Her ears were slightly pointed, likely due to having mixed elven blood.

Although they weren’t as prominent as an elf’s, they weren’t rounded like a human’s.
The part of herself that Leticia loathed, the part that the hero loved.

A human that was an elf. An elf that was a human.

That was Leticia.

Leticia Fonteau. The Magic Queen, the demon king slaying mage. She had had a pair of children with the hero.

Even so, her body had not deteriorated from doing so in the least. Rather, she seemed to have acquired a [Motherly] gloss.

Leticia was unusual for an elf, she liked white clothes.

Elves were called the people of the forest, and although they preferred bright green attire, Leticia wore a white dress.

Although the dress was decorated luxuriously, the cloth was thin and revealing, not hiding the queen’s body.

Her shoulders were bare, her rich breasts peeking out the top. However, the pure white dress covered her from her chest to her ankles.

Even so, with her slender arms, rich breasts, a waist that seemed as though it might break if one were to embrace her too tightly, and a soft rear that swayed gently, her charm and figure stood out with her tight-fitting attire.

Even just her hiding herself felt attractive.

Men that fostered lewd thoughts seeing her figure weren’t few.

Even the [Hero].

Even the hero she traveled with in her youth desired his traveling companions many times, both the mage Leticia and the hunter Frey.

She had realized her own beauty because of those days. That was when she first unconsciously used it as a weapon.

Nowadays, she used it intentionally.

Whenever she walked down the hall, men would turn their gazes towards her abundant and slightly shaking chest. Despite the protection of her clothes and undergarment, their bountifulness and tenderness could be understood just from looking.

It tempted male soldiers. A terribly invigorating feast for the eyes. Her beauty, body, and icy atmosphere that kept other nobles away.

Everything she was was beautiful.

An absolutely beautiful queen.

That was Leticia.

“Good morning, mother.”

The one to greet her was her daughter wearing an azure dress, [Melcia].

With silvery hair inherited from her mother, she wore an adorable expression. Her height was around one head shorter than her age group.

Even so, her chest. The part that could be called the symbol of a woman.

It was by no means how it was due to obesity. From her lovable face to her shoulders that could be called dainty, to her wealthy chest and waist that could be wrapped tightly in a corset without feeling any pain.

That was Mercia.

“Good morning, Mel. Do you have studies after this today as well?”

“Yes, mother. I’ll be getting breakfast, then going to school.”

“Is that so? Work hard.”


That was all for their conversation. The mother and daughter would only speak in passing of each other. Melcia bowed slightly, yielding the path.

To be royalty was troublesome. When she traveled with the hero, she was nothing but happy. Leticia lost herself in recollection.

There weren’t nobles or royalty or the like, they could speak as friends. They didn’t use formal speech and could act in a relaxed manner. They were very happy, dazzling, and beautiful memories.

She felt it might be good for her daughter to experience something like those times.
Although she understood why it was very difficult, it was still very troublesome to be royalty… as she walked while thinking about such things, she eventually reached a door.

She knocked on it lightly, but there was no answer.

Not minding it and deciding to open the door, she realized the door was locked and the doorknob wouldn’t turn. Even so, she seemed to understand and wasn’t surprised in the least, her glossy lips faintly weaving a spell.

Unlocking magic.

Although there was such a thing as privacy even considering family, she opened the door without minding it and entered the room.

There was a conspicuously large bed with a canopy above it in the room, a luxurious piece of furniture that shouted royalty.

Although Leticia’s family preferred simple rooms, the royal family’s appearances were important as well. Even in the case where it was a private room that likely wouldn’t be seen by other nobles.

There was a figure still on the canopied bed despite the sun already being up in the sky. Leticia approached and let out a sigh.


In truth, although this wasn’t something the queen should do but rather the chamberlain, that much wouldn’t cause Leticia to yield.

Waking up her children was a mother’s duty.

While gently shaking the bulge on the bed, she called out her name several times. After repeating that for a while, black hair crawled out from the bulge.

It was the exact opposite of Leticia and Melcia’s silvery hair. The darkness of night. A deep, deep black—the same hair color as the hero’s.

Her beloved daughter that inherited the hero’s blood, [Mariabelle].

She had glossy black hair and matching eyes. However, her smooth skin could cause even Leticia to concede, producing a magnificent contrast.

Although saying that one was being frugal and saving was good, she wasn’t dressed up in the least, wearing modest pajamas that were hopeless for royalty.

She felt that her daughter resembled her father, the hero, quite a lot. He also didn’t attempt to acquire anything but the essentials.

Although nobles didn’t view it that favorably, Leticia loved even that part of Mariabelle.

Seeing her child, she would remember the hero who was no longer with her. She was incredibly dear to her.

“Wake up. You’ll be late for school, you know?”

“… Mou, it’s that late?”

“Really now… just like your father, bad with mornings.”


With Leticia’s minor laugh, Mariabelle’s cheeks swelled slightly.

She didn’t like to be compared to her father. Even so, Leticia felt that her adorable appearance was suitable for her age.

However, that was something that couldn’t be helped. Thinking so, she patted her as though combing her soft hair.

“Fufu, you have beautiful hair.”

“But everyone at school says it’s disgusting.”

“Is that so?”

Black hair was rare in this world.

Rather, besides Mariabelle who was related to the hero, there wasn’t anyone else with it in the country.

Therefore it was regarded as a curiosity, to be feared, and to be found as strange.

It was incredibly sorrowful that the hero’s color was heresy in this world.

“Even so, one day, you will meet someone that loves this hair.”

“… I wish.”

With Mariabelle’s mutter that sounded as though she’d given up at some point, Leticia’s chest tightened.

Even though she loved her so much, her child was starting to hate the world.

However, that was something that couldn’t be helped. There was no such thing as a magic that could change hair and eye color in this world.

Therefore, Leticia caressed that very jet black hair. She did this in order to help her daughter understand she was loved.

Mariabelle also entrusted herself completely to that maternal loving, having her hair combed flat by her mother’s hands. Times like this were the only ones she loved.

Such peaceful times.

The demon king was defeated by the hero, and from then on peaceful mornings would continue for all eternity.

Such happy scenes would continue.




The magic kingdom, [Fonteau].

At its northernmost tip, there was a cave where a few years back, the magical silver [Mithril] was mined.

The magical silver had been completely mined out, so at this point, it was nothing but a cave; no one went near it.

It was stagnant and gloomy, sunlight not capable of reaching its interior. A place where the [Grudges] of people caught by sudden cave-ins and the like accumulated.

However, it wasn’t silent. Drops of water sometimes dripped from the cave’s roof, the screeches of bats echoing about as they roosted.

Bats making noises, water dripping against stone, and enough insects to cause women and children to shriek and run from the sight.

It was that sort of repulsive, filthy, gross, polluted, and stagnated place.

It was also, in a sense, peaceful. Bats flew around, disgusting insects crawled across the ground, and vengeful ghosts sang their despair.

Continuing even after the magic silver’s mining ended, it should also continue on well into the future.

However, it ended.

On this time of this day, that peace ended.


With a lower pitched sound than what they’d generally make, a bat fell to the ground. On the base of the neck of the bat that had fell, there was a single insect that couldn’t have been any larger than the size of a thumb.

A needle with paralytic poison on it appeared from its mouth, and thereupon, the insect ate its paralyzed prey. Taking several days to ascend the wall, it had used its body to climb little by little so that the bats wouldn’t notice, killing one with paralytic poison.

Finally catching its prey.

The insect did not have feelings, but it certainly let out a small sound of pleasure.

This was the natural law of nature. For all of time up until that moment as well as all time following.

—However, who would have expected for that very principle to produce the worst outcome?

The insect extended a thin tentacle from its mouth, preying on the felled bat.

The insect’s meal wasn’t that large. Dissolving the skin at the bat’s nape, it ate nothing but a small amount of the soft meat from there.

And thus its meal was over.

As for the remains, it would be eaten by insects that couldn’t climb the rocky wall or fell the bats.

There wouldn’t be anything remaining at all. They would eat even the bones.
Actually, the insects would collect at the bat’s corpse and—zuzu, there was a sound, as though something was just barely dragging along the cave. It was a tiny sound, at the level of not being audible to humans.

However, that sound and vibration caused the insects to scatter.

What had appeared in the cave’s darkness was a [Distortion]. A monster had been born.

Zuzu. A sound that until that point had not been heard in the cave.

Taking a closer look, it was like a mass of mucus that was clad in deep black, as though seeing a distortion in the cave’s darkness—a dark slime.

Several years ago when the demon king still lived, it wasn’t an unusual monster. Its academic name was [Black Ooze].

A middle class monster of the slime type, a strong specimen in its own right if it had lived for a long time.

However, that was if it had lived for a long time.

A newly born black ooze was inferior to even domestic animals such as dogs. They were only the size of a child’s fist.

Honestly it would have just rotted away, unable to catch any prey. It was likely destined to be eaten by the crowd of insects.

However, there was a prize in front of this slime.

Moreover, it wasn’t even something at the same level as itself, it was a big prize.
Following its instincts, the slime took the bat’s corpse into its own body. Slimes would take their prey into themselves to digest little by little, slowly nourishing itself.

It was lucky. And its fortune could also be called bad—it was unlucky.

It was the lowest class, an ordinary slime.

No, that would be the case for any other slime.

Without obtaining prey, the slime would have rotted away, unable to change its fate.

However, this black ooze obtained food.

And so, a change occurred.

The slime that was the size of a child’s fist instantly grew after taking in the bat.

This was the characteristic of a black ooze.

It could digest its digested nourishment into a mass increase instantly. Now that it had obtained the bat’s nourishment, the tiny slime was already unable to be killed by the insects.

—Right now there were bats on the ceiling of the cave that could kill the slime, or possibly the lizards and wild dogs around the cave’s entrance.

But this slime was smart. No, could it even be considered intelligent?

It wouldn’t set its sights on big prey, it would first ferret out the tiny insects from the rocks.

The size of a single insect was small, the increase to its mass from preying on them would be insignificant. Even so, the number of insects in the cave rivaled the number of stars in the sky.

It hunted and ate insects. Following its instincts, it voraciously and exhaustively ate and ate. Then, it increased its size.

After several days had passed, it crawled in the wall and captured a bat.

Although the living bat fought back, it wasn’t able to get away after being caught by the slime. And although the lizards would stab it with their fangs and desperately attempt to resist, these past days it had grown so large that they were now helpless against it.

It wasn’t able to digest the carapace of that insect that preyed on the bat from before. Moreover, since it was small, it gave very little nourishment.

However, the slime acquired an interesting ability. A paralytic poison strong enough to catch even bigger game than itself was added to the slime’s liquid.

Because of that, hunting became easier. The bats inside the cave, the lizards, and the insects had all been thoroughly eaten away by the slime, so it extended a tendril outside to a wild dog outside of the entrance.

It understood that its liquid had a paralytic effect. On alert, the wild dog ate a small piece before going into convulsions.

When it finished preying on the wild dogs in the vicinity, the slime returned to the cave. Although it didn’t understand anything like homing instincts, as far as the slime was concerned, this was its home.

Right now, the only things together with the slime in this cave were the grudges dwelling there. That was all.

Where an ordinary cave might be still and calm, this one had become a cave of death filled with the songs of vengeful ghosts.

At that moment, the slime had become the size of a cow.

Some years back in the period where the hero and the demon king fought, that size could occasionally be seen.

However, now that monsters weren’t appearing, things like a black ooze could only be seen in illustrations.

Everyone believed in their peace and that it would last eternally. They had finally passed the demon king’s age and wouldn’t give up their happiness.

That’s how it was.

Right now, no one realized that a monster had been born.

After that, a month’s time flew by.




It had come to the point where there were no more wild dogs to prey on outside and the residents of the nearby village began to wonder what was happening.

Although they had prospered as a mining town in the past, it had become impossible to collect magical silver so the city’s scale went from being called a town to a village.

Right now, there were only a dozen or so people living there. It was a country village that made a living by dairy farming.

Although there had been some wild dogs attacking the village’s cattle and putting the elderly people at a loss for what to do, they hadn’t turned up recently.
They were curious. Even though there was food in the mountain, that wasn’t enough to satisfy a wild dog.

After they’d tasted cattle, they had obstinately attacked their cattle. Although a lot were killed by snare traps, it wasn’t enough to guard their cattle.

There were a large amount of wild dogs after all.

And yet none had shown up recently.

Did they give up?

Although someone asked that, it was immediately denied. Wild beasts wouldn’t hold such respectable thoughts.

However, it was a fact that they hadn’t attacked. It was a mystery, but they decided to treat it as one of Goddess Euswara’s miracles and offered her their prayers.
They were like a country village. Even so, in this kind of country village, there was an energetic old man.

Taking up arms, he wore his equipment and headed out to the mountain. His goal was to see what had happened to the wild dogs. Although the other villagers tried to stop him, the old man didn’t listen to them.

This old man believed that he was strong. He had killed countless monsters in his youth. Setting aside slimes and goblins, he’d even taken on and defeated monsters many times his size like ogres and the like with his comrades.

Even though he wanted to grow old, his strength had never dulled—or so he believed.

He started to climb the mountain. Losing his breath, he sat down on a rock to take a rest. It was harsh for an aged body to climb a mountain.

Gulping down water as though bathing in it, he took a deep breath. He’d already climbed a surprising amount of the mountain. Beyond this lied only the mithril tunnel.

However, he still hadn’t come across the wild dogs. Rather, he hadn’t seen any wild rabbits either.

What was going on?

His intuition told him that something was happening.

Even if he wanted to grow old, his intuition just improved. However, his body had grown old and tired.

—When he noticed it, his body couldn’t move.

Paralysis. His aged body couldn’t notice the slight stimulus as the paralytic poison flowed into him.

The effect showed immediately. Paralytic poison coming from a slime the size of a cow was much too strong for an old man.

To say nothing of moving his body, even his heart stopped. The old man, not knowing what happened to him, died.

And so the slime preyed on the old man.

Slowly, ever so slowly.

… And so, the curtain of the worst case scenario rose.

On this day, the black slime acquired knowledge. Knowledge about monster killing, knowledge about humans, knowledge about life… and about sex.

Right now, no one realized this slime existed. This slime had mutated. It could steal the unique characteristics of the things it ate.

Like that insect’s poison.

Like human knowledge.

If the first human it had eaten were a woman—

It that had happened, it would have stolen the characteristic of [Pregnancy], so the worst case scenario was avoided.

However, even though the first one it had devoured had grown old, it was a human male.

The slime obtained things. Knowledge of humans, knowledge of life—knowledge of impregnating women.

Humans were sinful things.

Not to mention their own race, humans would conceive children with all kinds of races: elves, sirens, even beastkin.

The world still didn’t know.

In this world where there was no demon king to produce monsters, a monster had been born.



<- Illustrations | ToC | Next Chapter ->

  1. Play on words, ‘genius’ and ‘natural calamity’ are pronounced the same in Japanese.
Recommended Series