Steel is hard. And with each passing day, it evolves.
The forces of the Metallum Empire, which had defended against the slime soldiers of the Aqua and Silva Empires alongside the Terra Empire and advanced as far as Silva’s border, returned to their own camp.
But Metallum did not rest.
More precisely, it had no time to rest.
In the central control room of Metallum’s fortress, the current running across the metal plates suddenly began to flicker rapidly.
Belkar shouted.
“Warning! Intense heat detected from the southeast! It seems Ignis is coming again!”
Agnon hurriedly operated the equipment.
“Preparing barrier defensive posture.”
Peron followed up.
“This time… they’re bringing a variety of troop types. In addition to single-attribute soldiers, there are golden soldiers, and…”
He examined the machine closely, then continued.
“This is a fusion of fire and wood.”
Crasso and the steel assemblers also moved in haste.
“We will build additional defensive fortresses with the crystal cores.”
Oruma, Emperor of Metallum, did not react strongly.
He had already known that Ignis would come for them again.
It was only that the timing was a little sooner than expected, and he had not anticipated the scale.
“First, produce as many crystal infantry as possible and deploy them to the front.”
His voice was calm.
“We will be able to test the power of the crystal cores right on time.”
The steel assemblers stationed at the border moved all at once.
They fused crystal cores with the wave cores of Aqua that Terra had additionally secured, then began consuming those cores to construct crystal defensive fortresses.
At the same time, crystal infantry were also produced.
One assembler asked Crasso.
“Representative, is Terra not sending support?”
Crasso answered briefly.
“They have no such ability. Our empire will be defended by us.”
His gaze slowly moved along the newly constructed crystal defensive wall.
“…Instead, they are giving us something better, so that is enough.”
Not long afterward, a report arrived from Commander Carden.
“Ignis forces are in sight. Contact is imminent.”
Agnon shouted.
“All units, commence battle! They will not break through us this time either!”
At last, a red line began to spread slowly across the distant horizon as it approached.
The temperature of the air was already higher than usual, and the metal plates on the ground were vibrating faintly from the heat.
Peron shouted.
“Wait, those are… embers! Soldiers fused from fire and wood!”
The charred infantry produced from ember cores were advancing while spewing dark blue smoke from their entire bodies.
Agnon shouted.
“Put the crystal infantry on standby!”
Before long, they arrived in an instant.
The crystal infantry and the charred infantry swung their arms at one another and grappled.
Crack! Paat!
They were evenly matched.
The charcoal composing the bodies of the charred infantry shattered against the hard crystal, but its heat was also sufficient to melt the crystal.
Whoosh, thud! Pat!
It was still impossible to judge which side held the advantage.
However, in terms of numbers, the crystal infantry were slightly more numerous.
The crystal infantry were also suffering heavy losses, but the charred infantry were nearing annihilation.
“More are flooding in!”
Carden shouted.
“Those appear to be golden soldiers!”
Now the fusion infantry of the golden cores reached Metallum’s border.
“Another two-attribute soldier!”
The few crystal infantry left after taking heavy losses joined forces with the steel knights to block the fusion infantry.
But Oruma did not lose his composure.
“They put forward the soldiers they were most confident in. The ones that come after will be easier to fight.”
Unlike the fusion infantry, the charred infantry possessed the possibility of suppressing the energy of metal by utilizing the mutual insult relationship through the energy of wood.
However, the metal energy possessed by the fusion infantry could not harm the same metal, so they had to face them solely with the energy of fire.
Even so, what was clear was that the fire energy possessed by the fusion infantry was stronger than that of troops with only the single fire attribute.
“The golden soldiers are aiming for the central area!”
Commander Robic shouted.
“Their fire has taken form. Even a collision alone could cause heavy damage to the walls!”
Metallum’s soldiers drove Ignis’s forces back even more fiercely.
They fought in silence, yet inwardly, they harbored fury.
From Metallum’s perspective, Ignis had produced golden cores using metal cores stolen from them, then returned after producing golden forces from those very cores.
“Those… should have been ours…”
A steel knight muttered to himself.
“Bastards like you dare to wield gold…! I will never forgive you!”
The steel knight order pushed even farther forward and swung their hammers at the fusion infantry.
After Ignis’s relentless assault, the crystal defensive fortress eventually fell as well, but they too had few forces remaining.
Now mechanical throwers joined in behind the steel knights, hurling projectiles at Ignis’s soldiers.
The last to appear were the Crimson Flame Knights.
Without slowing down, the Crimson Flame Knights surged through the gap in the broken defensive line.
The flames they emitted were no less fierce than those of the fusion infantry.
“Do not let them in any farther!”
Carden shouted, and Metallum’s forces swiftly readjusted their positions.
The steel knights and mechanical throwers endured the pain of their bodies melting under the blazing fire and did not retreat.
The unceasing pressure of flame.
But steel blocked that fire.
“Hah, it seems they have nothing left now.”
The battle was slowly showing signs of nearing its end.
Through the sacrifice of countless soldiers, the flames could no longer penetrate Metallum’s territory and gradually died down.
Agnon said.
“The fire is retreating!”
Just as he said, Ignis’s soldiers were withdrawing.
Only hazy smoke remained in the places where they disappeared.
“They’re gone!”
“We defended it again!”
The remaining soldiers of Metallum still held their positions while maintaining order.
Clank, clank, clank.
All around them was loud with the sound of commemorating victory.
Peron said to Oruma.
“Your Majesty, however, we will not last long in this state.”
Oruma nodded.
“Of course. We will prepare a new density.”
He turned and headed for the fortress.
The underground laboratory within the fortress.
Metal cores and earth cores were arranged side by side inside a tank.
The two kinds of cores silently pressed down with only their weight.
“We have finally found the answer.”
Researcher Keldren murmured in a low voice.
Beside him, Renma was operating the tank.
“Metal core, waveform frequency stable. Earth core, accommodation structure stability secured. Contact in 3… 2… 1…”
Metal was hard, and earth was heavy.
They were different, but both shared the common quality of being solid attributes.
When the fusion began, a resonance spread instead of vibration.
The wave that filled the space carried a firm consistency.
“Density, matched. Fusion result structural stability, confirmed.”
A moment later, the space quieted as though contracting.
A single core bearing a gray sheen quietly revealed itself inside the tank.
“Base structure, earth. Internal cohesion, metal. Overall reactivity, strength-focused bias.”
Keldren said.
“This is different from the existing metal core. One could say its weight itself is its power.”
Oruma said quietly.
“A fusion of metal and stone. In that case, its name shall be the Iron Ore Core.”
The name given to the two-attribute core fused from a metal core and an earth core, containing both the energy of metal and the energy of earth, was the Iron Ore Core.
Oruma immediately ordered the researchers to produce Iron Ore Cores.
“Now fuse Terra’s remaining cores into Iron Ore Cores.”
“Yes, understood.”
Peron said to Oruma.
“But we also have Silva’s cores. They are spoils obtained from our last advance into Silva.”
After hearing his words, Oruma called Keldren.
“I will give you a new task. I will deliver Silva’s cores to you, so proceed with fusion research on them as well.”
“Yes, I shall obey.”
The amount of life cores Metallum had plundered from Silva was not large.
Even if the research proceeded successfully, producing a troop type seemed impossible.
As Oruma left the laboratory, he said.
“Terra will provide us with as many cores as we need. We will begin full-scale production of a new troop type.”
The development of technology for the Iron Ore Core was swift.
The steel assemblers built an iron ore barracks in an open lot.
“It seems easier to construct than the crystal barracks.”
“That must be because we already have experience doing it.”
Soon, within Metallum’s territory, a barracks emitting a gray sheen was constructed.
Agnon approached the barracks.
“This barracks can also produce soldiers directly from cores, then.”
He slowly inserted an Iron Ore Core into the input port.
After several Iron Ore Cores were inserted, the entire barracks vibrated at regular intervals.
From within came the noise of something being assembled.
A short while later, the wall was pushed aside, and a form resembling armor made of a mixture of iron plates and rock appeared.
Crasso said.
“Constituent material: steel structure. Reinforcement device: rock structure. Movement and reaction speed are not fast, but its weight is overwhelming… The name of this soldier is Ironclad Infantry.”
The Ironclad Infantry slowly took a step forward.
The ground sank low, then rose back again.
A form as hard as steel and as unmoving as the earth.
Peron said with satisfaction.
“As expected, this structure is sturdier than our existing troop types. These will be even more resistant to fire.”
Oruma approached them and nodded.
“Good. Earth does not block fire, but neither does it aid it like wood. If it can become more resistant to fire, then that alone has meaning.”
Soon, numerous Ironclad Infantry began emerging from the barracks in rows.
The newly born soldiers lined up in perfect order all at once.
Oruma looked at them.
“Metal does not speak. But even without speaking, its existence alone has more than enough value.”
Oruma and his retainers gathered in the meeting room within the fortress.
“You have all worked hard.”
Oruma spoke first.
“Following the crystal core, now the Iron Ore Core. In particular, if possible, we will be able to continue producing Iron Ore Cores. As long as Terra continues to provide us with cores.”
Peron said.
“Moreover, we have now secured Silva’s cores as well. However, it would be difficult to say their numbers are sufficient. If we are to produce a troop type and deploy it to the front immediately after core fusion, we would need at least as many as Terra handed over…”
After thinking for a moment, Oruma said.
“There is no hurry. Silva’s cores will not be very useful in suppressing those Ignis bastards. What we actually need more are crystal cores. How many crystal infantry remain right now?”
Agnon answered.
“There are 10 crystal infantry left in reserve. The crystal infantry deployed in the battle against Ignis were annihilated.”
“I understand.”
Oruma rose from the throne.
“Those Aqua bastards—if they had listened to my request earlier, I might even have dissuaded Terra instead. Yet now that the situation has turned unfavorable, they come crawling to us.”
He paused briefly, then began again.
“In any case, supporting Terra remains unchanged even now. I, too, wish to follow what Terra seeks.”
Once again, a newly accumulated weight in the world was testing the center.
Terramont also heard the signal of the birth of the Iron Ore Core.
“How many does this make now? How many remain ahead…?”
He silently looked up at the ceiling.