Two days after Kiraboshi-san’s apprenticeship was decided.
Kageichi immediately took her to a back alley—a rundown corner that didn’t seem very safe—and entered a dilapidated house with a dimly open Gate.
The structure was a “Cave” type Dungeon.
A standard cave type with jagged rocks lining the walls.
“Now, Kiraboshi-san. As I mentioned, we’ll start with some basic training today.”
“Y-yes! …So, this Dungeon? Is this our workplace for today?”
“No. Today we’re visiting a Dungeon called a ‘Den’ in the industry. …Well, since we’re here, let’s start with an explanation from there.”
While slowly advancing through the Dungeon, which resembled an underground cave with jagged rocks, Kageichi put his hand to his chin and pondered.
“Basically, there are several common specifications for what we call Dungeons. …They have an internal, expanded alternate dimension. There are Creatures called Monsters. There are various types of stages, such as ‘Caves’ and ‘Forests’. And if left unattended, the Monsters inside the Dungeon will multiply and eventually lead to a Gate Crash.”
“That’s when Monsters come out on the surface and cause damage, right?”
“Yes. If Dungeons didn’t have a negative impact on the surface in the first place, the government wouldn’t bother spending money to exterminate them.”
In fact, when Dungeons first appeared, governments around the world paid close attention to them as new “resources.”
Even though Monsters appeared in the Dungeons, they were new territories and new types of items that didn’t exist in the modern world.
There was no way the government wouldn’t take action.
Also, the Monsters themselves were initially seen as new life forms, and applications in various fields were expected.
…As a result, it was found that all Monsters were beings based on Magical Power and were non-living entities without even DNA.
So far, this is a review of general knowledge.
“By the way. Have you ever heard of Rank S Dungeons or Rank A Dungeons, Kiraboshi-san? The ‘Nagi Plains’ we’re going to challenge next week is also one of the Rank S Dungeons.”
“Yes, it’s a very large Dungeon in Japan designated by the government, right? I heard that no one has cleared it yet…”
Kiraboshi frowned there, as if thinking, “Huh?”
“Sensei. Now that I think about it, anyone can enter the Rank S Dungeon ‘Nagi Plains’ from the Gate in front of the station, right? I went there during Dungeon studies in physical education class…”
The lower levels of the Rank S Dungeon “Nagi Plains”—approximately floors 1 to 5—are open to the general public.
If you ask a dedicated Hunter, even amateurs are allowed to enter the Dungeon for sightseeing; that’s how relaxed it is.
Besides, more than five years have passed since the Rank S Dungeon appeared.
…And yet, there have been no reports of Gate Crashes.
There are several reasons for this.
First, the government properly manages and regularly exterminates the Monsters in the Dungeon.
Second, Rank S Dungeons have extremely high Magical Power content, so even if the number of Monsters increases somewhat, they won’t fall into a Gate Crash.
In short, it’s just a vast but easy-to-manage Dungeon.
“There are some Dungeons, including Rank S Dungeons, that are unlikely to cause Gate Crashes. These are called ‘hits’ in the industry and are used as valuable resources.”
For example, they can be used as training grounds for Skills.
Or, they can be used for “farming,” where Monsters that appear regularly are defeated to obtain a certain amount of dropped items.
Large amusement facilities can also be attached, allowing people to enjoy entertainment within the Dungeon.
“And there are also rare wild Dungeons that have low intrusion into reality and are unlikely to have a negative impact. This Dungeon also falls into that category.”
“Hee…”
“And if you wanted to, people could live in such Dungeons. Moreover, this Dungeon hasn’t been reported to the Labyrinth Agency. In other words—it’s a hideout for social outcasts and criminals.”
“!?”
“They’re perfect for practice. No one cares if they die.”
“?!?!?”
“We must make effective use of resources,” Kageichi said as he walked on calmly, but wait a minute.
Isn’t the flow of the conversation strange from the middle?
“U-um… Sensei? The opponents we’re practicing with today are… Monsters, right?”
“Yes. They’re Monsters. More importantly, let’s get to the main topic.”
“There was a dangerous topic before the main topic.”
“What I’m going to teach you today is the most fundamental and important technique in Dungeon exploration. It’s commonly known as ‘Detection’.”
Kiraboshi frowned at the unfamiliar word.
Kageichi ignored it and lightly raised his index finger.
“The greatest danger in a Dungeon is, after all, encountering enemies. It’s especially dangerous if it’s a surprise attack. Conversely, if we can always make the first attack 100% of the time, the advantage is obvious. What makes this safe and secure idea a reality is the search for spatial Magical Power. It’s a skill commonly known as ‘Detection’.”
“Detection.”
As the name suggests, it’s the skill of sensing the opponent’s Magical Power and noticing their presence in advance.
The other day, when he implanted the Numbers and predicted the Monster’s attack, it was also due to this skill.
Unlike Skills and Abilities, it’s an important technique that anyone can learn with training.
While explaining, Kageichi handed her a penlight-shaped magic tool.
“Sensei, what is this?”
“When you press the switch on the handle, a weak Magical Power is emitted from the tip, and it bounces back. It’s like echolocation for bats, or the Magical Power version of active sonar. First, use it to grasp the sensation of emitting weak Magical Power and receiving it. …By the way, it’s easier to understand Magical Power by relying on your sense of touch, smell, and heat rather than your eyesight.”
“Try using it to explore the surroundings.”
As Kageichi instructed, Kiraboshi held the pen in reverse and glared at the crossroads ahead.
…Kiraboshi had learned about the sensation of Magical Power itself in Dungeon class in high school.
Imagine that a force flowing through your body—like life energy—envelops your entire body, and then manipulate it…
The “Detection” that Kageichi was talking about was the act of emitting that Magical Power and confirming the opponent’s presence by listening to the echo.
“The Magical Power emitted by Detection should be as thin as possible. Amateurs sometimes blast Magical Power thinking they’re Detecting, but blasting active sonar is like picking a fight. In the first place, you’ve already lost if the opponent realizes you’re ‘Detecting,’ so do it with that kind of determination.”
Kiraboshi illuminated the jagged cave and the crossroads that spread out beyond it with the penlight.
She released her own Magical Power in a small amount and felt the vaguely returned echo with her ears and skin.
She closed her eyes.
Vaguely, Kiraboshi’s skin felt a tingling, a jagged Magical Power echo that was typical of caves. In addition to that…
A heat-sensing Magical Power reaction from behind.
Kiraboshi stiffened with a start.
She had been walking straight through the Dungeon, but—
“Don’t turn around. Don’t let the opponent know you’ve noticed.”
“…”
“And from now on, I’m going to do something. Can you sense that too?”
Hearing that, Kiraboshi gripped the penlight again and searched the surroundings. She gasped.
Before she knew it, there was a heat reaction behind Kageichi.
A round object shaped like a pot lid was set in the ground…?
Immediately after, heat stirred behind Kiraboshi.
She reflexively turned around. What Kiraboshi saw was a grinning, filthy man with a beard grabbing a club-like object and trying to strike her—and,
Pi-peep
“Hegyowa!?”
He was blown away before her eyes and slammed into the wall.
The man stopped moving.
“…………”
“I increased the power to make it easier to search, so his Magical Power should be completely depleted. He shouldn’t be alive.”
“Eh. Did you kill… him…?”
So easily…?
Kageichi gently said to the pale-faced Kiraboshi, “Please rest assured.”
“I just exterminated a Monster. There’s no problem.”
“Eh. But that person is human…”
“He’s a Monster.”
“Ehh…?”
“They speak human language and have thoughts similar to humans, but they have no hesitation in harming others. In other words, they’re Monsters, so we should clean them up.”
“No, that—”
“Besides, Kiraboshi-san, you have some idea, right? About the existence of Monsters in human skin.”
Kiraboshi was startled.
…The sisters she burned down the other day.
When she asked Shirogasaki-san later, she heard that they were of course alive and hospitalized in a Dungeon-related hospital—
“Detection is important to counter such evil existences. Always stay one step ahead and overwhelm the enemy unilaterally before they can attack. That’s the key to conquering Dungeons safely, securely, and without Stress.”
The meaningless word “fair play” is not in Kageichi’s dictionary.
Inflict 120% damage on the enemy, and wait leisurely without any damage on our side.
For that purpose, Kageichi Futsuu is the kind of man who will use anything, be it insecticide spray or a surprise mine, no matter how cowardly it may seem.
“I’m not a serial killer who enjoys murder. It’s just that I’ve taken the best measures to live comfortably in this world, and that’s how it turned out… but it’s surprisingly hard for people to understand.”
“…………”
“Now, let’s continue through the Dungeon. Use ‘Detection’ to sense the next monster.”
“Eh?” Kiraboshi’s eyes widened again.
…There are still… people in this Dungeon?
“The only ones in this Dungeon are villains who harm society. Those who don’t report the Dungeon’s appearance to the government and suddenly attack us should disappear for the sake of society. Let’s make effective use of our limited human resources.”
“B-But the opponents are people…”
“If you can’t do it to people in practice, you can’t do it in the real thing. …However, it would be too much to start on the first day, so shall I do the cleaning today?”
Kiraboshi “Detected” Kageichi setting up a second mine as if it were the most natural thing in the world.
Then, Kageichi started humming a little tune.
She realized that even that humming was to lure the enemy into complacency, and immediately after, an explosion and a scream erupted behind them.
She might have become a disciple of someone truly terrible.
He’s the kind of person who would recommend a flamethrower to a High School Girl, so I knew he wasn’t normal, but not to this extent.
…But.
This might be the strength I need, Kiraboshi thought, clenching her fist with a slightly pale face, and continued through the dimly lit Dungeon with her teacher—the two of them successfully exterminated nearly ten monsters that day.
Of course, they left no evidence behind.