About a hundred years ago, dungeons suddenly appeared all over the world.
Some spread out beneath the earth, while others took the form of towers or ruins.
Inside them lurked ferocious monsters and minerals no one had ever seen, and that endlessly expanding 『unknown』 fascinated countless people.
As a result, people who explored dungeons never stopped coming, and injuries and fatal accidents occurred one after another.
Across the world, legal frameworks such as the Exploration Regulation Act were put in place, and exploration became a license-based profession.
A global standard was established for the Explorer license, and explorers were ranked from E to S, with restrictions placed on which dungeons each rank was allowed to enter.
Using data from the explorers who had entered them, dungeons were classified as beginner, intermediate, advanced, or special, based on their internal structure and the danger level of the monsters that inhabited them.
Many of the special-class dungeons, incidentally, were still unconquered.
Explorers’ motives varied.
Some made a living selling magic stones and ores obtained by defeating monsters.
Others headed for unexplored dungeons, seeking out materials and monsters no one had ever seen.
Still others streamed their expeditions and aimed to become influencers.
And Narakino Rakuna, a rookie explorer, was also slowly making her way through a dim dungeon while streaming.
Her goal was to become popular and make friends.
For an explorer who lived with danger to her life at all times, that goal might have sounded a bit frivolous to others who heard it.
However, she herself was completely serious, and she had spent five years preparing for this.
Now, at last, she had taken her first step.
The beginner dungeon Rakuna was traversing had relatively few monsters and was judged to contain no dangerous ones.
In addition, the layout inside the dungeon was simple, so it was almost impossible to get lost.
It was, in every sense, a dungeon for beginners.
Even so, it was rare for anyone to attempt their very first expedition solo.
“…Ah.”
Rakuna, who had been walking along without incident and making steady progress, came to a stop for the first time.
—Bzzzzzzzzn.
Floating in midair ahead of her, blocking her path, was a monster.
It was a huge, fly-type monster, about fifty centimeters long, called a Bugs.
Swaying its body lazily from side to side, it filled the air with the hum of its wings.
“…So there are bugs inside dungeons too.”
Even though this was the first monster she had run into, she did not look particularly surprised.
Muttering softly, she took off the backpack from her shoulders and began rummaging through it.
“Got it,” she said when she found what she was looking for and pulled out a spray can.
After shaking it vigorously with both hands, she started spraying herself with it in one go.
“I’m glad I brought bug spray.”
She closed her eyes and sprayed with a refreshed expression, but only for a moment.
The Bugs came straight toward Rakuna, utterly unconcerned by such things.
Bugs were a familiar sight on beginner explorers’ streams.
Monsters that looked like giant versions of ordinary insects almost always drew screams from novices.
Because they were not especially dangerous, some 『scream-lovers』 among the viewers even affectionately referred to them as 『scream-manufacturing monsters』.
However.
The novice explorer Rakuna raised the spray can in her hand high over her head and brought it down on the lunging Bugs.
There was a sharp pop.
At the same time, the Bugs’ body vanished.
In its place, several small magic stones scattered across the ground.
“Whoa. So inside a dungeon, even bugs turn into stones and disappear. Just like monsters.”
Of course, Bugs were not insects but monsters.
Letting out a little “hoooh” as if satisfied with her own mistaken conclusion, she slung her backpack on again and started walking.
But this time she spotted a monster farther in and immediately stopped.
It was a small, boar-type monster called an Uribon.
The Uribon fixed its gaze on Rakuna and stared at her.
“Ah, I guess that’s a monster. But I’ve never seen that one before… All right.”
Muttering to herself, she picked up a stone that was lying on the ground.
“Let’s start with a little warm-up!”
With that, she hurled the stone at the monster.
The moment the stone hit, there was another sharp pop.
Just like the Bugs from earlier, the Uribon turned into magic stones in an instant.
“Eh!?”
The thrower herself let out a cry of surprise.
Then she stood there in silence for a while, her mouth half open.
Still not really understanding what had just happened, she decided for the time being to start walking again.
She ran into two more monsters after that, but both vanished under her litt-le-warm-up stone throws.
After that she did not encounter any more monsters at all and simply kept walking and walking.
“…Dungeons really are huge, huh. …What do I do, I’m starting to get hungry.”
Every dungeon always had a central great hall that served as its core.
The so-called boss room.
If the monster in that boss room was defeated, the dungeon would quiet down, and for the next week no monsters would spawn from that dungeon.
This phenomenon was what people generally referred to as clearing a dungeon.
Incidentally, in the beginner dungeon she was currently in, the boss room lay just beyond an iron door, but Rakuna had failed to notice it and had been wandering endlessly around the same area.
Normally anyone would have noticed it right away, but she had unfortunately walked past it several times.
She had a hopelessly terrible sense of direction.
“Hmm… I don’t really get it, but I’m not running into monsters anymore, so maybe I should just go home? I’m hungry anyway…”
Rubbing her stomach, she looked around, trying to find the way back.
Then, as if suddenly realizing something, her eyes flew wide open.
“…Ah…!”
Her previously clouded expression brightened in an instant, and she jogged over to the wall.
Pressing her ear against the rough stone wall, she murmured softly, “Here.”
And in the next moment—
—DOOOOOOOOOM!
A massive tremor and the sound of destruction echoed through the dungeon.
Rakuna was standing with her fist thrust out toward the wall.
In the wall there was now a gaping hole just big enough for a person to pass through.
Debris from the shattered wall lay scattered all around.
“I knew it. A way out.”
Having smashed the dungeon wall to pieces with her fist, she nodded with a satisfied little snort.
Her huge backpack kept getting stuck, but she squeezed into the hole she had opened up herself and somehow managed to wriggle through to the other side.
She let out a breath and was about to start walking when—
『—Bee-bee. Warning. A 『Connection』 has occurred within the dungeon. This dungeon is currently classified as an upper-class dungeon. It is extremely dangerous, so please immediately—』
The red tracking drone that had been at the entrance was now rushing toward her, blaring its warning.
As the red tracking drone came at her from behind at tremendous speed, Rakuna—
“Nooooooooooooooooo!”
—let out a full-throated scream and, spinning around, lashed out with a slap.
—SMAAAAAAAAACK!
The red drone, struck by the Mach-speed slap, fell to the ground while spinning at high speed.
It rolled along, crackling with pale blue sparks.
Then it let out a hiss as black smoke rose from its body, and it stopped moving altogether.
Face pale, Rakuna nervously peered down at the crumpled red drone.
“…That really scared me… It suddenly started talking, so I thought it was a person and hit it on reflex… What do I do…”
Her brows drooped into a troubled eight-shape as she fell silent for a moment.
But she quickly faced forward again and shook her head.
“Well, what’s done is done… Yeah, for now I’ll just go home. I’m hungry. And after I eat, I’ll go and apologize.”
She clenched her fists with both hands and gave a big nod. “Yeah!”
And just like that, she proceeded on—deeper into the dungeon.