The waves surged at an unforeseen turn of events, and those waves reached the forest.
The deep-sea laboratory located beneath the fortress of the Aqua Empire.
This was not the laboratory situated on the border adjoining the Silva Empire, but Aqua’s own independent laboratory.
Inside the laboratory, Chief Researcher Birellen and Senior Researcher Mirel were watching two kinds of cores.
“We’ve found the wave of the flow……”
Birellen carefully placed the earth cores atop a transparently condensed plate.
“By nature, earth blocks our water. However, it can also be made to hold our water.”
Behind them, Empress Nereia and her retainers were watching.
Nereia asked Birellen.
“Are all the preparations complete?”
“Yes. We will begin.”
Within the clear, cool deep sea, the energy of the earth cores spread.
Dark-brown soil was moving along with the flow of water.
“Wave Core and Terra Core. Begin resonance. Maintain circulating flow.”
Birellen spoke softly, and Mirel slowly inserted the earth core and the Wave Core into the cylinder in turn.
“No matter how much earth rejects water, in the end, it will have no choice but to accept it.”
For a moment, no one spoke, as if time had stopped.
Then, when wave and earth collided at the center of the cylinder, a small vibration arose, and soon a single core, cloudily flowing in an ocher color, filled that place.
“Finally, earth……”
Mirel reacted in a tone filled with awe, but Birellen simply stared at the core in silence.
The earth was moving.
The earth that had remained fixed in place within the core flowed like water.
Neither solid nor liquid, a sphere holding an energy that was not fixed, yet did not collapse.
Birellen said,
“This is not self-circulation. It is a structure that moves by embracing the flow of our water.”
Nereia quietly nodded.
“Water may cover earth, but it is rare for earth to hold water.”
Naus added,
“We are facing that rare moment right now.”
Nereia gently lifted the core into her hand.
“The name of this core is the Mud Core.”
“Mud……”
Sian peered into the newly born Mud Core.
“Earth that holds water. Indeed.”
Nereia instructed the researchers.
“Produce more Mud Cores, but only enough to experimentally produce one or two soldiers. We do not have a great need for mud forces.”
“Yes, understood.”
Nereia and her retainers rose above the surface.
Sian asked her,
“How do you plan to use the remaining Terra Cores?”
“Nothing has been decided yet. However, it is unlikely we will create additional Mud Cores.”
The site for the barracks to be constructed with the Mud Core was an area north of the capital, Nereis, and was not geographically favorable.
That was how little the mud troops had been considered a unit type to have expectations for from the very beginning.
Levian said,
“Then I will insert the Mud Core.”
Nereia nodded.
Soon, the Mud Core inserted into the barracks writhed like a living organism and began to form a certain shape.
At first, it was nothing more than muddy water floating on the surface, but as it gradually condensed, it became a little more solid.
Thus, the first Mud Infantry was born.
The Mud Infantry possessed fluidity similar to Slime Infantry, but because its interior contained matter formed from coagulated earth, with every step it sank deep beneath the surface and sent out waves.
Naus muttered to himself.
“Even seeing it directly, I don’t think it suits us……”
Sian, as if he had not expected much either, opened his mouth in a reluctant tone.
“This can be seen as the limitation of a core fused from mutually opposing relationships. And since we are the inferior side in that relationship, it seems it will be even more difficult to handle.”
Earth blocks the flow of water.
Thus, mud, which contained the energy of earth, was the same.
The Mud Infantry belonged to Aqua, but it was in fact more dangerous to Aqua than to Terra.
The Mud Infantry barely maintained its posture while floating on the surface.
Nereia’s voice rang low.
“Mud is not gentle like water. Rather than flowing, mud is an existence that endures its own weight. It may become a threat even to allies, so monitor it thoroughly.”
“Yes, I will keep that in mind.”
Levian bowed his head to her.
Following Nereia’s command, only three Mud Infantry were produced outside the barracks.
Their steps across the surface were slow and heavy.
“Huh?!”
Levian flinched in surprise.
Naus also looked in the direction Levian was watching.
“Something is approaching……!”
Nereia also turned to the east.
Sensing that something was wrong, her expression changed.
“That is Terra’s……”
A colossal being was approaching the eastern border.
More precisely, the border dividing the Aqua Empire and the Silva Empire.
“Something…… is trying to cut off our exchange.”
Nereia’s voice trembled.
Then Levian shouted,
“That is Terra’s Yellow Dragon! The one said to appear from the final-stage barracks……”
Nereia ordered him.
“Train as many troops as possible and concentrate them on the eastern border!”
“Understood! May I deepen the barracks?”
“Do so.”
Since Aqua’s fortress had already been deepened to Stage 4, the barracks could also be deepened to the same stage.
With the production of Slime Cores temporarily halted, a certain number of Wave Cores had accumulated.
Sian hurriedly began deepening the barracks.
Inside the barracks, a whirlpool raged, and its scale expanded beneath the surface of the deep sea.
As if it were trying to expel a gigantic being, the barracks scattered its existing structure while simultaneously forming thicker and wider walls.
Levian closed his eyes with an anxious expression and focused on the flow.
The location of Terra’s Yellow Dragon, Montanus, was roughly detected.
“Hmm?”
Levian opened his eyes again.
“The Yellow Dragon has stopped for a moment. It seems to be waiting for something.”
“No.”
Nereia said,
“Montanus is now looking over the world. Originally, barracks are facilities that train citizens into soldiers, and barracks built with two-attribute cores give birth to soldiers from the cores themselves. However, a dragon is born as an existence in itself, not as a citizen. Montanus has merely stopped in order to read the world.”
Levian asked her,
“Must we also summon a dragon immediately?”
Nereia closed her eyes slightly and answered,
“It would be good if we could, but circumstances do not permit it. First, we must train the new unit type and do our best to stop Montanus.”
Sian shouted,
“The deepening is complete!”
Levian moved immediately.
“I will begin training at once!”
At last, the fourth unit type of the wave line was about to appear.
As if rising from the deep sea, enormous pillars of water surged upward, then gathered together and slowly condensed into a certain form.
Kwaaaaa……
With the sound of a great wave, the walls of the barracks trembled.
It was a movement trying to create something entirely different in size from before.
After some time, it revealed itself.
A form twice as large as the previous unit type, the Tidal Warrior, with a savage appearance as if it would devour whatever stood before it.
It seemed to embody a storm beyond a tidal wave.
With whirlpools contained within its body, two arms stretched forward, and two legs supporting its frame.
Levian said in a low voice,
“This is the Tempest Behemoth.”
The three fins rising from the beast’s back swayed according to its movements, and its eyes were the very sense that perceived currents without looking at the surface.
Levian continued,
“It is a being that brings storms, with the ability to draw in ocean currents and release them all at once.”
Nereia nodded.
“Understood. Produce as many Tempest Behemoths as possible. We must stop Montanus with them as much as we can.”
“Understood.”
While additional Tempest Behemoths were produced with the remaining Wave Cores, Nereia and her retainers focused on the movements of the Yellow Dragon Montanus.
“It has begun moving again.”
Levian said.
“But is the reason it is deliberately coming northeast to keep both us and Silva in check at the same time?”
Naus answered,
“That appears to be the case. Furthermore, Terra seems to be trying to test us now. If they had intended to attack us, they would have sent the Yellow Dragon north immediately, but they sent it northeast, and its speed is not especially fast.”
Nereia said,
“Montanus is not an existence that moves under anyone’s orders. Its movement now is entirely of its own will. Terramont also does not appear to have given Montanus any particular orders. And the destination it has chosen is precisely the place where the border between us and Silva lies.”
Sian looked around at them and spoke.
“Can we stop it on our own? Our Tempest Behemoths may be strong, but the opponent is the highest-grade unit type with the energy of earth. So……”
All the retainers watched Nereia’s expression.
They were hoping for a certain decision from her.
Nereia closed her eyes for a moment, then spoke quietly.
“The flow must be connected. To where it has always flowed.”
The approach of Terra’s Yellow Dragon, Montanus.
It led to a single conclusion.
“It may be difficult with only us.”
Nereia still had her eyes closed.
The Silva Empire, from which they had once grown distant.
Yet the life of those who symbolized nature had always been together with water, and now, it was also the only breath that could stand against the center.
“Drian……”
Nereia softly called her name.
“We must face each other again. Earth is trying to block our flow. The place that flow must head toward is still
the forest alone.”
She looked east.
They had to seek out Silva again.
Levian said,
“We must go right now. If we are any later, the Yellow Dragon will block our path.”
Nereia nodded.
And behind her, one of the Tempest Behemoths approached and quietly lowered its neck.
She gently placed her hand on the beast’s body.
“Let us take them as well. It would be best to show them that we are still strong.”
Levian answered,
“Yes, I think so as well.”
The Tempest Behemoths were not merely forces to be stationed at the border between sea and forest.
They were also a symbol of Aqua’s trust.
Nereia and her retainers headed toward the Silva Empire together with three Tempest Behemoths.
The trees on the outskirts of the Silva Empire were trembling faintly.
But that was not only because of the wind caused by the Yellow Dragon.
From beneath the earth, vibrations of metal striking the ground were being transmitted.
Empress Drian of Silva was also aware of the Yellow Dragon’s existence, but they were facing a more immediate problem.
“Metallum……”
She spoke in a low voice.
At that moment, from behind, Bramir spoke with bated breath.
“Your Majesty, Aqua is approaching us.”
Drian did not turn around.
“Yes, it must be because of Montanus. But right now, protecting the forest comes first.”
“That is not all. Ignis is also approaching the southern border.”
Drian flinched in surprise.
“Why are they coming again?”
“We do not yet know. If they are here to demand something of us, then we must refuse for now.”
The Empress of Aqua and her retainers, the army of Metallum, Terra’s Montanus, and even the unidentified group from Ignis.
They were all approaching Silva at the same time.