200 - The Underpass

The vibration traveling through the underground valley grew stronger until dust began falling from the ceiling in continuous streams. The inhabitants of the settlement moved with practiced efficiency rather than panic. Warriors closed the nearest gates, civilians were directed toward the inner districts, and several groups hurried toward the western channel carrying equipment that looked more like mining tools than weapons.

Commander Varik remained beside Subin, watching the dark passage.

"How long until it reaches us?" Subin asked.

"If it follows the western channel, perhaps ten minutes."

"Then why isn't everyone leaving?"

Varik looked at him.

"Because this isn't the first time."

Another tremor passed beneath their feet.

"The creature comes through the western channel whenever the mountain network becomes overloaded. Usually it passes through the outer tunnels and disappears into the northern territories. This time, however, the channel has been carrying far more mana than normal."

Ara immediately understood.

"The new road."

Varik nodded. "Since it appeared, the western channel has been receiving additional flow."

Subin looked toward the ceiling.

The pattern was becoming familiar. The newly formed routes were not isolated roads. They were changing how mana moved through the surrounding geography, sometimes pushing creatures toward regions that had remained stable for generations.

"Can the channel handle it?"

"Normally, yes. But something has blocked the secondary outlet."

Ara brought up her map. "Where?"

Varik pointed deeper into the settlement.

"Beyond the lower district."

The answer was enough.

Subin turned toward the expedition.

"We clear the outlet first. If the creature reaches the blocked section while the pressure is still rising, this entire valley could be damaged."

Varik immediately agreed, and his warriors joined the group.

They moved through the underground settlement while the tremors continued. The city was far more extensive than it had appeared from the entrance. Houses were carved directly into the walls, elevated bridges crossed enormous gaps, and workshops operated around natural crystal deposits. Unlike Aetheris, which depended on floating islands and aerial circulation, this civilization had adapted itself to the mountain's interior.

Ara kept scanning the surrounding structures as they moved.

"This city was built around the channel."

"Yes," Varik said. "Our ancestors settled here because of it."

Subin noticed that several buildings had been reinforced with thick metal supports.

"Has the pressure increased before?"

"Never this quickly."

They reached a broad chamber where the western channel disappeared beneath the settlement. A massive stone structure stood over the opening, but one side had collapsed inward, blocking nearly half of the passage.

Mana was forcing its way through the remaining gap.

Ara examined the obstruction.

"Natural collapse?"

"Probably caused by the recent route formation," Varik replied. "We tried removing it yesterday, but the pressure was too strong."

Subin stepped toward the blockage.

"Then don't remove all of it."

Ara looked at him.

"You're thinking of redirecting the flow."

"Yes."

The damaged section was not merely debris. Some of the fallen stone had become saturated with mana and was now acting like a partial barrier. Removing everything at once would release the accumulated pressure into the settlement.

Subin studied the structure for several seconds before drawing Simple Edge.

Instead of cutting through the obstruction, he made a series of precise cuts along its upper section, creating narrow channels through which the excess mana could escape. The first opening released a powerful stream of blue energy, followed by a second and third. As the pressure gradually decreased, Varik's engineers moved in and reinforced the weakened structure.

The difference was immediate.

The ground stopped shaking.

Ara checked her readings.

"Pressure is dropping."

Varik watched the restored channel with clear surprise.

"You understood the structure after looking at it for less than a minute."

Subin sheathed his sword.

"The damage wasn't complicated."

Jae-hyun smiled.

"That's probably the most Subin answer possible."

Before anyone could respond, the western tunnel erupted.

A deep roar rolled through the underground valley, followed by a violent surge of air that extinguished several lamps along the chamber walls.

Varik's expression became serious.

"It's here."

The creature emerged from the darkness.

At first, only its horns were visible.

Then its enormous head pushed through the tunnel, followed by a body covered in layers of dark stone-like armor. It had six powerful legs, a broad chest, and a long tail lined with crystalline plates. Every step drove cracks through the tunnel floor.

The system identified it.

Deepstone Behemoth

Level 256

Rank: A+

The creature did not charge.

It stopped at the mouth of the tunnel and inhaled deeply.

Its eyes moved across the chamber before settling on the mana channel.

Ara lowered her scanner.

"It's following the mana."

Varik nodded.

"It isn't hunting us."

The distinction did not make the creature harmless.

A Level 256 A+ monster inside a confined underground settlement was still an enormous threat.

Rafael raised his shield.

"If it keeps moving forward, the city will be damaged."

"We need to redirect it," Subin said.

Varik looked toward the northern tunnel.

"There is an unused passage."

"Where does it lead?"

"To the old mining region."

"Open it."

Varik hesitated.

"That passage hasn't been used in decades."

Subin looked at the Behemoth.

"We don't have decades."

The warriors moved immediately.

Several mechanisms were activated along the northern wall, but the ancient gate remained stuck.

The Behemoth stepped forward.

The floor shook.

Subin moved toward it.

Yerin immediately followed.

"Subin."

"I'm not going to fight it."

He stopped several meters from the creature.

The Deepstone Behemoth lowered its head.

Its horns pointed toward him.

Subin kept his sword sheathed.

Instead of projecting killing intent, he allowed his sword intent to spread lightly through the ground. It was not an attack. It was a controlled signal, a way of making his presence clear without provoking the creature.

The Behemoth hesitated.

Its head turned slightly toward the northern wall.

Subin noticed.

"It can sense the channel."

Ara understood.

"The old passage."

Subin nodded.

"If we open it, it'll follow the stronger flow."

The gate mechanism finally responded.

A heavy stone door began lifting.

Mana rushed through the opening.

The Deepstone Behemoth immediately turned.

It walked toward the northern passage.

The creature's massive body passed within several meters of the expedition, but it did not attack. Subin maintained the same restrained sword intent until the Behemoth disappeared into the old tunnel.

Only after the sound of its footsteps faded did everyone relax.

Varik exhaled.

"That was easier than expected."

"It could have gone badly," Rafael said.

Subin looked at the damaged western channel.

"It didn't because we fixed the reason it came here."

Ara returned to the channel and checked the readings again.

"The flow has stabilized."

She paused.

"Mostly."

Subin looked at her.

"What's wrong?"

"The western channel is receiving energy from another direction."

She enlarged the map.

A secondary line had appeared beneath the underground city.

It extended westward, then curved north.

"That wasn't there when we arrived."

Varik stepped closer.

"Impossible."

Ara shook her head.

"It's real."

The line continued beyond the limits of her map.

Subin studied it.

"Can you determine where it goes?"

"Not yet. The signal becomes stronger the farther north it travels."

Varik's expression changed.

"Our northern territories are mostly abandoned."

"Why?"

"The old mines collapsed generations ago. There was no reason to return."

Subin looked toward the tunnel where the Behemoth had disappeared.

"Maybe there is now."

Varik remained silent.

The expedition had already found more than a new road. Beneath the western mountains existed an entire underground civilization, functioning mana infrastructure, and a network extending into territories that had been abandoned long ago.

But there was no reason to rush deeper.

They needed a map first.

Ara spent the next several hours surveying the underground settlement while Varik provided information about the surrounding territory. The western route connected to the surface road they had entered through, while the northern passage led toward the old mining region. The third route descended deeper beneath the mountains and was still used occasionally by local miners.

The deeper route was the one Varik considered most dangerous, not because of any specific monster, but because sections of the tunnel had collapsed over the years.

Subin marked it for later.

They returned to the surface settlement of Westfall the following morning.

Edrin was waiting.

When he saw the expedition return safely, relief crossed his face.

"You entered the Underpass."

"Yes."

"And?"

"There is a civilization beneath the mountain," Subin said. "They're called the Underpass people. They control three major routes."

Edrin looked toward the mountains.

"Our ancestors used to speak about them."

"You knew they existed?"

"Only as stories."

Ara gave him the updated map.

"Now they're confirmed."

Edrin studied it carefully.

"What did you find beyond their northern route?"

"We haven't explored it."

The old man nodded.

"Perhaps that is for the best."

Subin looked at the western road.

The road had returned to its original position after sunrise.

Whatever altered it at night, it was now stable again.

That gave them something they had not had before: a predictable route into the western underground region during daylight.

Sel contacted Crossroads.

The report would change the city's map considerably.

A new western route.

Westfall.

The Underpass civilization.

Three underground routes.

A functioning mana network.

And a northern region that had been abandoned but was now receiving renewed mana flow.

Director Kang appeared on the communication device.

"Do you recommend immediate exploration?"

"No."

Kang seemed surprised.

Subin continued, "We'll establish contact first and map the western route properly. Then we'll determine whether the northern route is safe enough for an expedition."

Ara nodded.

"There's too much information missing."

Subin looked toward the mountains.

They had spent weeks moving from one region to another, discovering regulators, settlements, roads, and ecosystems. Each new area added another piece to the map, but the World Dungeon remained far larger than anything Earth had explored.

For now, the western route was enough.

They returned toward Crossroads before sunset.

Behind them, the road remained open.

Far beneath the mountains, the Deepstone Behemoth continued along the old northern passage.

And somewhere beyond the abandoned mines, the newly awakened mana channel continued carrying energy into a region that had been silent for generations.