It had been about ten minutes since we left the hotel. We had cleared the urban area and transitioned onto the mountain road leading toward the dungeon, but there, we hit a light traffic jam.
"It’s pretty backed up," I muttered.
"Yeah," Yuji agreed. "Was there always this much traffic on this road?"
As Yuji and I grumbled, growing weary of the taxi’s constant stopping and starting, the taxi driver overheard us and explained the situation.
"Sorry about this, folks. This road is always like this at this time on weekdays."
"On weekdays?" I asked.
"Yeah. You kids look like students, right? I take it you usually only come out here on the weekends?"
"That’s right. We have school during the week."
When I confirmed we were students, the driver nodded understandingly and continued.
"It’s the same for everyone else. This time of day is the commute for the explorers who belong to companies that collect dungeon products. It’s especially bad on Mondays after the weekend break."
"...Ah, I see."
I nodded, the explanation making perfect sense. Independent explorers like us, or those who treated it as a hobby, could choose our own hours, but those tied to a company were subject to strict working hours. Whether they were full-time or on a shift system, companies were bound by the Labor Standards Act, which regulated employee hours.
If a dungeon exploration company forced its corporate explorers to stay in a dungeon for a week straight on official orders... the Labor Standards inspectors would probably come charging through their front doors with glee.
"So, I’m sorry to say, it’ll be a little while longer until we arrive."
"Understood. We’re in no rush, so please just focus on driving safely."
"You got it. Leave it to me."
I gave the driver a small bow.
After taking nearly twice as long as usual, we finally arrived at the taxi drop-off point in front of the dungeon. We quickly unloaded our gear and stretched out our stiff bodies.
"Finally..."
"That was way more crowded than I expected," Yuji sighed.
"It’s a single-lane road with no side paths, so it can’t be helped," Hiiragi-san added.
Hearing her, we looked back at the snaking line of vehicles still waiting to enter the parking lot. It made me wonder if they shouldn't just implement traffic control at the base of the mountain road.
Once we saw the taxi off, we picked up our gear and started toward the building housing the changing rooms.
"Still... the atmosphere is definitely different than usual."
As we walked, we looked around, feeling a slight sense of displacement. The vibe of the dungeon was worlds away from its weekend persona.
"You’re right," Yuji said, scanning the area. "It’s hard to put into words, but... there’s no slack. None of that casual, weekend air."
"I think the difference in their clothing and equipment plays a big part in that," Hiiragi-san noted. Her brow furrowed slightly as she pinpointed the source of our unease.
Just as they said, most of the people walking around were wearing matching uniforms emblazoned with corporate logos. The sheer professionalism of the equipment they carried was on a completely different level compared to the explorers we had seen the day before.
As we watched with curiosity, a group emerged from the direction of the parking lot.
"Hey, those are... follow-type transport robots, aren't they?"
"Yeah," I replied. "I think I saw them on some corporate promotional program. They said they’re essential for exploring while gathering items."
"Didn't they say one of those costs several million yen?" Hiiragi-san whispered.
The sides of the robots—each about the size of a tatami mat—bore a corporate logo. It belonged to a major dungeon exploration company frequently featured in TV and magazines.
A man leading a group with three of these robots noticed us staring and stopped to strike up a conversation.
"Hey there. Good morning."
"O-Good morning..."
Startled by the sudden greeting, I gave a quick bow. What did he want?
"You kids look like students. Should you be skipping school?"
"Oh, no... we have a makeup holiday today because of our sports festival, so it’s fine."
"Ah, I see. Sorry about that. I didn't mean to startle you. I just saw some young kids I didn't recognize on a weekday and couldn't help but wonder."
"Ah, no, it's fine..."
I realized then that he suspected us of playing hooky to dive into the dungeon.
It made sense once I thought about it. Not long ago—well, just a few months back—there had been a major controversy regarding a surge in students repeating grades. The primary reason for many of them was a lack of attendance or failing grades caused by an obsession with dungeon exploration. Consequently, the public perception of explorers took a hit for a while. People claimed that "playing explorer" led to academic failure. Even though the root issue was a lack of self-discipline, the entire explorer community was treated as if they were responsible.
Since that controversy was still relatively fresh, I suppose it was only natural for an adult to check on minors at a dungeon on a weekday.
"S-Still, that’s some impressive equipment," I said, trying to steer the conversation. "Using three transport robots like that..."
"Ah, yeah. They're something, aren't they?"
The man seemed to pick up on my attempt to break the awkward tension. He smiled and offered a brief explanation of the machines.
"This is an Advance Co. A-02. It’s the latest follow-type transport robot, boasting a maximum load capacity of a thousand kilograms!"
"Heh... a thousand kilos. That's a lot of weight."
"It is. On top of that, it’s equipped with eight in-wheel motor Mecanum wheels, allowing it to move in any direction instantly. It’s a lifesaver because you can move it out of the way fast if a monster attacks."
"I see. But... what do you do about changing floors? It doesn't look like it could make it down a flight of stairs."
"Ah, that..."
The man gave a confident smirk and signaled to one of his companions, who had been quietly observing our exchange.
"When we hit stairs, we do this."
He pointed at the robot, and it immediately began to transform. To the sound of whirring motors, eight pillars extended from the base, and the robot’s height shot up by about two meters in an instant.
"It grew?!" Yuji and I exclaimed in unison.
"Haha, surprised you, did it?"
Satisfied with our reaction, the man signaled his teammate again. The pillars retracted just as quickly, returning the robot to its original height.
The speed of the transformation was incredible. I stared at the machine, impressed.
"As you saw, we use that function to keep the cargo bed perfectly level while we navigate stairs."
"That’s amazing. But how does it move up and down so fast? I didn't see any pistons for a lifting mechanism."
"It uses chain rods to move. They're motor-driven and retractable, so the response time is excellent. When the sensors detect a step, the chain rods on all eight wheels adjust individually to maintain balance."
Now that he mentioned it, I remembered a TV program featuring something similar. They’d said it was energy-efficient and many times faster than hydraulic systems. I think they mentioned it was even used for stage lifts in theaters.
Seeing our genuine interest, the Team Leader continued his boast.
"The cargo bed also has an ultra-low-temperature freezer and a refrigerator. It lets us preserve monster meat drops and even bring in fresh food for ourselves."
"You can freeze things right on the spot?"
"Yeah. The purchase price changes based on freshness, you see. For our company, the quality of our monster meat is a major selling point."
"I see... are the other two equipped the same way?"
"No, we split their roles. The others carry our base supplies and equipment."
Hearing it explained from a professional’s perspective made me realize just how much effort went into logistics. At the same time, it highlighted just how broken my Spatial Storage skill was. Even with all this high-tech equipment, they couldn't hope to match the sheer volume I could carry in my inventory.
I reaffirmed my decision to keep Spatial Storage a secret until some equivalent skill or item became common knowledge.
"But with all those functions, does the battery actually hold up? Moving, lifting, and running freezers must eat a lot of power."
"With a conventional battery, you'd be lucky to get a few hours out of it. With a conventional battery, that is..."
"...So there’s a different power source?"
"Exactly."
I looked at the robot and thought. A power source other than a battery? Surely they weren't using an internal combustion engine in the semi-enclosed environment of a dungeon. If it wasn't a battery, maybe a fuel cell?
"This latest model uses a temperature-difference generator powered by a Core Crystal."
"A Core Crystal?!"
"Yeah. We put water and crushed Core Crystals into a test-tube-sized ultra-high-pressure vessel and heat the water to a supercritical fluid state of 374 degrees. We then guide that heat to a power generation element. Depending on the size of the Core Crystal and the environment, it can run continuously for about a week."
So Core Crystal power generation technology was already hitting the market. It wasn't just the monster meat and drop items; seeing new technology developed from dungeon materials becoming a reality showed just how much dungeons were being integrated into the world's infrastructure.
As I stared at the robot with a mix of awe and complicated feelings, the Team Leader scratched his head.
"The downside is that because it uses a high-temperature heat source, someone on the team has to have a boiler technician license to operate the power system."
"A license?"
"Yeah. It’s not a hard one to get, but it’s an extra step. Still, the benefits are more than worth it. Having hot meals and cold drinks inside a dungeon... well, you won't find anyone complaining about that."
"I suppose not."
Hot meals in a dungeon... that was a luxury worth any amount of paperwork. Usually, dungeon food consisted of light, preserved dry goods or high-calorie snacks. This became even more true the deeper you went. Unless you were an outlier like us, day trips were impossible once you reached the deep floors. I could see why a wealthy explorer would want one of these.
"Um, Team Leader? We really need to get going or we'll be behind schedule..."
"Ah, sorry. Well, there you have it. Sorry for taking up so much of your time, kids."
"No, thank you for sharing. That was really interesting."
The man, who had raised a hand to acknowledge the Team Member pointing at his watch, offered a final friendly word. Despite the initial suspicion, the conversation about the robot had been genuinely enlightening.
"We’re off, then. You kids work hard, and make sure you don't get hurt out there."
"Thanks. You too. Take care."
We waved goodbye as we headed for the changing rooms and they headed for the dungeon entrance.
Once Yuji and I reached the changing room and checked in, we talked about the team we'd just met while we geared up.
"I guess if you're trying to turn a profit as a corporate organization, you have to use machines like that," Yuji noted.
"Yeah. Without them, you'd have to rely entirely on manual labor. No matter how much stronger an explorer gets from their level, there’s a limit to how much they can carry when they have to worry about fighting monsters."
"And you can't just keep adding more porters," Yuji added. "More people means more food and supplies consumed inside the dungeon. Indiscriminately increasing the party size is a losing strategy."
"Which means equipment like that is going to become the standard for professional exploration."
"Probably."
I imagined a future where transport robots scurried through dungeons like they owned the place. It felt more like a factory than an adventure.
Once I finished changing, I did a final check of my gear. Everything was in order.
"Alright, I’m ready. You, Yuji?"
"Done."
"Then let’s go."
"Right behind you."
I locked my locker, and Yuji and I stepped out of the changing room together.
Time to do my best today, and hopefully, come back in one piece.