149 - Where the River Meets the Sea

Chapter 149 — Where the River Meets the Sea

The information from the Japanese research team changed the atmosphere at breakfast.

The previous day's mission had been straightforward. They had entered the northern Japanese dungeon, observed its circulation system, documented the developing ecosystem, and returned without causing unnecessary damage. Everyone had expected the next step to be analysis and perhaps a second reconnaissance mission after several days of observation.

Instead, the underground mana network had changed during the night.

A section of the dungeon's circulation system had diverted toward the coast.

The projected route ran beneath several kilometers of forest and mountainous terrain before approaching the sea.

Takeda Renji stood beside the digital map in the temporary command room while the researchers displayed the latest readings.

"The flow isn't moving randomly," one of them explained. "The underground channel has expanded in a relatively straight direction. The mana density is increasing as it approaches the coast."

Subin studied the map.

"How much?"

"Approximately forty percent higher than yesterday."

Min-seok frowned. "Forty percent?"

The researcher nodded. "The increase began about six hours ago."

Jae-hyun folded his arms. "Could it reach the ocean?"

"It probably will."

Yerin looked at Subin.

"What happens if it does?"

Subin didn't answer immediately.

The question was simple, but the answer wasn't.

The dungeon's underground system had already demonstrated that it could use existing environmental structures to transport and stabilize mana. Rivers, groundwater, stone formations, forests, and mineral deposits had all become part of the circulation network.

The ocean represented something entirely different.

It was enormous.

If the dungeon's mana reached seawater, the area available for circulation would increase dramatically.

"It depends on what the ocean does with it," Subin finally said.

Min-seok looked at him.

"Meaning?"

"If the mana disperses, nothing significant may happen. If the ocean absorbs it and forms a stable circulation route, the dungeon could begin influencing a much larger area."

Ara's expression became thoughtful.

"Marine monsters."

"Possibly."

Renji looked toward the researchers.

"Can we stop the flow?"

The room became quiet.

Subin shook his head.

"Not before we understand it."

Min-seok sighed.

"There it is again."

Yerin smiled slightly.

"He really doesn't like destroying things he hasn't understood."

"I've noticed."

Subin ignored them.

"How far from the coast?"

"Approximately twenty-eight kilometers."

"And how fast is it moving?"

"At the current rate, it could reach the coastline within eighteen to twenty-four hours."

Jae-hyun immediately straightened.

"Then we don't have much time."

"We have enough time for observation," Subin said.

The room turned toward him.

He pointed at the map.

"The river is moving through an existing underground system. If we enter from the dungeon side and follow it, we can determine whether the flow is naturally expanding or being redirected by pressure."

Renji nodded.

"Agreed."

The second expedition was smaller.

Subin, Yerin, Min-seok, Ara, Jae-hyun, Renji, and three Japanese A-rankers entered the dungeon again.

The rest remained at the surface to monitor the external mana readings.

This time, the atmosphere inside was different.

The previous route had been familiar.

Now the underground river had changed.

Its water level had risen by several centimeters.

The blue light beneath the surface was also brighter.

Subin crouched beside the river.

"Mana density is increasing."

Yerin looked at the water.

"How much?"

"Approximately twenty percent compared with yesterday."

Jae-hyun looked ahead.

"That's a lot."

"It is."

They moved quickly.

The first section was still peaceful.

The Frostscale Wolves from the previous day were nowhere to be seen, but several smaller creatures had appeared near the river. Their levels were higher than before.

A small crystal-backed animal that had previously been Level 48 was now Level 51.

Ara noticed it.

"They're growing."

Subin nodded.

"Naturally."

"That quickly?"

"The environment is providing them with enough mana."

Min-seok looked at the creatures.

"So if the river keeps expanding..."

"The entire ecosystem will become stronger."

Nobody spoke for a few seconds.

They continued deeper.

The underground forest looked different too.

Some of the trees had grown several centimeters overnight.

Their roots had spread farther into the stone.

The leaves carried a faint blue glow.

Subin stopped beneath one of them.

He placed his hand against the trunk.

Mana flowed through it.

Not randomly.

The tree was pulling mana from the river, filtering it, and releasing a weaker concentration into the surrounding soil.

The process reminded him of Greenfall.

But there was a major difference.

Greenfall had been an established ecosystem.

This dungeon was building itself while they watched.

Subin removed his hand.

"It is adapting."

Yerin looked at him.

"To the mana?"

"To everything."

They continued toward the coastward channel.

After nearly an hour, the river divided again.

This time there were three branches.

The original channel continued forward.

A second flowed toward the eastern mountains.

The third moved downward.

Subin stared at the third channel.

"That's new."

Renji checked the map.

"The coast is that direction."

Subin nodded.

The team followed it.

The passage descended sharply.

The temperature dropped.

The stone became wet.

Soon they heard something they hadn't heard before.

A distant roar.

Everyone stopped.

Min-seok reached for his axe.

Jae-hyun's sword came halfway out of its sheath.

Renji raised his hand.

The sound came again.

It wasn't a monster's roar.

It sounded like water moving through a massive underground chamber.

They advanced carefully.

The passage suddenly opened.

Below them was a cavern larger than the previous day's underground forest.

But there was no forest here.

There was an underground lake.

The water was dark blue.

Mana moved across its surface in thin glowing lines.

At the center of the lake stood a massive crystal formation.

The crystal rose nearly thirty meters from the water.

It wasn't absorbing mana.

It was directing it.

Subin immediately understood.

"This is a junction."

Ara looked at the structure.

"Like the one in Kazakhstan?"

"No."

Subin walked closer.

"The Kazakhstan network transferred mana between regions. This one is controlling pressure."

Jae-hyun looked at the lake.

"What does that mean?"

"The dungeon has reached a point where its internal circulation can't keep expanding through a single route."

Subin pointed toward the crystal.

"So it created a regulator."

Renji looked at the three surrounding tunnels.

"And the regulator is deciding where the mana goes."

"Yes."

Min-seok frowned.

"Can it send mana directly into the ocean?"

Subin looked toward the eastern tunnel.

"Probably."

Before anyone could respond, the water beneath the crystal moved.

A ripple spread across the lake.

Then another.

The mana concentration increased.

The researchers' instruments began producing warning signals.

"Mana pressure rising!"

Subin stepped backward.

"Everyone move away from the lake."

The team obeyed.

The water began rotating around the crystal.

A massive shape appeared beneath the surface.

Two enormous eyes opened.

Min-seok raised his axe.

A creature emerged slowly from the lake.

It had the body of a serpent, but unlike the sea serpents they had encountered before, its body was covered in dark blue scales with translucent fins extending along its sides.

Its head alone was larger than a truck.

The creature rose until half of its body towered above the water.

The system registered it.

[Abysswater Serpent]

Level: 127

Rank: A+

The serpent stared at them.

Nobody moved.

Subin studied it carefully.

Its mana wasn't aggressive.

It wasn't preparing to attack.

It was guarding the junction.

Yerin tightened her grip on her spear.

"Subin."

"I know."

The serpent opened its mouth.

Instead of attacking, it released a deep vibration.

The water around it responded.

The entire lake trembled.

Ara's eyes widened.

"It's communicating with the environment."

Subin nodded.

"Not necessarily with us."

The serpent turned toward the crystal.

Its body wrapped around the formation.

Subin understood immediately.

It wasn't a guardian created to protect the dungeon.

It had chosen the location because the junction provided a stable supply of mana.

The dungeon and the creature had become mutually beneficial.

The serpent protected the junction.

The junction fed the serpent.

Another natural relationship.

Subin lowered his sword.

"We aren't fighting."

Min-seok looked at him.

"You sure?"

"Yes."

The serpent watched them for several more seconds.

Then it lowered its head toward the water.

The pressure in the chamber decreased.

Subin looked toward the crystal.

The regulator had stabilized.

Renji exhaled.

"That was close."

"It wasn't going to attack unless we threatened the junction."

Jae-hyun looked at Subin.

"How do you know?"

"I don't."

Jae-hyun raised an eyebrow.

Subin smiled faintly.

"I observed its behavior."

That answer made Jae-hyun laugh.

"You're becoming more annoying."

"I've been told."

The team spent another thirty minutes collecting readings.

They discovered that the junction was directing approximately thirty percent of the dungeon's mana toward the coast.

The rest remained within the mountain ecosystem.

The distribution was remarkably stable.

There was no immediate danger.

They returned to the surface.

The Japanese researchers immediately surrounded them.

"What happened?"

Renji gave them the preliminary report.

Subin added one important conclusion.

"The dungeon isn't simply expanding."

The researchers listened.

"It's establishing a circulation network."

He pointed toward the coastline on the map.

"If the ocean accepts the mana flow, the dungeon may stop being a localized phenomenon."

One researcher swallowed.

"How large could it become?"

Subin looked at the map.

"I don't know."

That answer was more concerning than any number.

The Association decided against stopping the river.

Instead, they established monitoring stations along the projected route to the coast.

The mission was officially classified as controlled observation.

The international team would remain in Japan for another two days.

That evening, Min-seok challenged Renji to a sparring match.

The two fought in the temporary training arena behind the Association facility.

Subin watched from the side with Yerin.

Renji fought with a single katana.

His style was clean and economical.

Min-seok used broad axe swings and heavy footwork.

The first clash produced a sharp metallic sound.

Renji stepped aside before the axe completed its arc and struck toward Min-seok's shoulder.

Min-seok twisted and used the axe handle to block.

He countered with a horizontal swing.

Renji jumped backward.

"You rely heavily on force," Renji said.

Min-seok smiled.

"And you rely heavily on not getting hit."

"That is generally useful."

Yerin laughed.

Subin watched carefully.

Renji's swordsmanship wasn't stronger than his own.

But it was refined in a different direction.

His movements were based around minimal commitment.

He didn't attempt to overpower attacks.

He made opponents spend more energy than necessary.

Subin remembered something similar from his fight with Seo Jin-ho long ago.

Human swordsmanship had taught him something monsters couldn't.

Every swordsman had a history.

Their techniques reflected their experiences.

Renji eventually lost the sparring match.

Min-seok landed a clean strike against his shoulder.

But Renji smiled.

"I understand why people talk about you."

Min-seok lowered his axe.

"Because I won?"

"Because you fight differently from what I expected."

Subin smiled.

Min-seok looked toward him.

"What?"

"Nothing."

"You were thinking something."

"Maybe."

The evening continued peacefully.

Later, Yerin and Subin walked along the quiet road outside the facility.

The sky was clear.

The mountains were dark silhouettes against the moonlight.

"You've changed," Yerin said.

Subin glanced at her.

"How?"

"You used to be much more impatient."

"I was?"

"Yes."

"When?"

"Before I met you."

He smiled.

"You knew me for a very short time before the changes."

"Still."

She walked beside him.

"You always wanted to move forward."

"I still do."

"I know."

She smiled.

"But now you seem more comfortable stopping."

Subin thought about that.

"Maybe because I understand that stopping isn't always falling behind."

Yerin looked at him.

"That's a surprisingly mature answer."

"I can be mature."

"Sometimes."

He laughed.

They continued walking.

After a while, Yerin reached into her pocket and touched the small wooden sword pendant he had given her.

Subin noticed.

"You still wear it."

"Of course."

"You don't have to."

"I know."

She looked at him.

"That's why I do."

Subin didn't answer.

The two continued walking in comfortable silence.

Neither of them needed to fill every moment with words.

Meanwhile, beneath the mountains, the dungeon continued changing.

The underground river moved steadily toward the coast.

The flow had not reached the sea yet.

But the monitoring stations detected another change.

The projected arrival time had shortened.

It would reach the ocean sooner than expected.

And for the first time, the Japanese Association prepared to observe something no one had witnessed before.

A dungeon's mana network meeting the open sea.

Subin looked at the updated report the following morning.

He closed the tablet.

"Let's go."

Yerin smiled.

"Another observation?"

"Another observation."

Min-seok picked up his axe.

"And if something attacks?"

Subin stood.

"Then we'll deal with it."

This time, nobody disagreed.