The Allied Army advanced deep into the heart of the plains.
In the meantime, they had repelled numerous ambushes and destroyed every small orc settlement that stood in their path. The battles hadn't been difficult.
It seemed things were progressing smoothly—until the very thing they had feared occurred.
Their supply lines were cut.
The supply unit, which had been delivering rations to the Allied Army via Gid and Balshad, no longer appeared.
The orcs had blocked the route.
Yuri muttered,
"That's unfortunate."
But it wasn't a major issue.
The Allied Army had stockpiled enough supplies.
"There's an order to be more vigilant with supply protection."
"Naturally."
The Allied Army had drawn very close to Okua.
They were now within striking range—close enough that it wouldn't be strange if the orcs brought their entire force and attacked at any moment.
A decisive battle was bound to happen soon.
"Raymond."
"Yes, sir."
"What do you think that is?"
Yuri, while marching, pointed toward the horizon.
Something huge, like a boulder, was jutting out from a densely overgrown patch of land. Its sharply angular shape made it unlikely to be naturally formed.
"I'm not sure."
Raymond tilted his head.
"That stone looks similar to the ones we saw in Balshad…"
"Doesn't it?"
"Then, could it be man-made?"
Just as Yuri was about to answer—
The ground trembled.
Horses reared up in fright, and the marching soldiers bent at the waist all at once to steady themselves. Weapons clattered to the ground with a metallic ring.
"Everyone, stay calm!"
Leaping off his horse, Yuri braced himself against the ground and assessed the situation.
The tremor continued.
Fortunately, there was nothing nearby that could collapse.
Suddenly, the flag of Briol, set by the standard-bearer, began to tilt.
Yuri activated his mana method and rushed over to grab the flagpole.
"I-I'm sorry, Your Highness."
"It's fine."
The soldier in charge of the flag had stumbled and fallen, unable to keep his balance.
Yuri set the flag upright again and looked around.
The entire Allied Army was rattled and panicked by the quake. A few flags from other nations were seen falling.
Yuri grinned.
"We can't let the flags fall. We've got an image to maintain. Right?"
"I'm sorry!"
"Ah, I wasn't blaming you."
The earthquake, which had seemed like it would soon end, persisted for a while before finally stopping.
Yuri handed the flagpole back to the standard-bearer and checked on the unit.
The knights were unharmed, and while some soldiers had fallen, their injuries were only minor.
Yuri moved through the troops himself, calming the unsettled atmosphere.
Once things were mostly under control, Laurent approached.
"Your Highness."
"Hmm?"
"Look over there."
Laurent pointed toward the horizon.
"Huh?"
The boulder-like shape they had seen earlier had changed. The buried portion had risen above the surface, towering like a hill.
"What is that?"
Dirt kept crumbling off the elevated section, gradually revealing its overall shape.
It was a stone structure.
Its architecture resembled what they had seen in Balshad.
It looked like ancient ruins.
"Makes me curious."
"Shall we take a look?"
"Yeah. It's best to check it out."
Staring at the ruins, Yuri spoke.
"Then we'll need permission."
Yuri was struck by a sense that he had to see it for himself.
The plains still held many secrets.
Those ruins might prove helpful in confronting Okua.
Yuri visited Ragna with Laurent.
The Empire was handling the situation with relative calm.
Even the soldiers, along with the ominous black-armored knight order, quietly organized their gear.
"Totally opposite of Bursen."
When they passed by earlier, Bursen's camp had been in complete chaos. Froin had been running around screaming that this was an omen of catastrophe.
As Yuri appeared, the knights' gazes suddenly shifted toward him.
"Quite the stares we're getting."
"Indeed."
"Seems they admire your valor, Your Highness."
"Yeah, right…"
Soon, Ragna, who had been checking the unit status, appeared.
"Yuri. Everything alright?"
"Yes, sir."
"An earthquake out of nowhere… Strange."
"It really is."
"What happened?"
"Well…"
Yuri relayed what he had seen at the front.
Ragna then stood atop his horse and looked through a telescope toward the horizon.
"There's definitely something out there."
"If you permit, I'd like to investigate it myself."
Either way, the Allied Army would be passing by the structure as they continued their march.
"The sun is setting anyway. Spending the night near those ruins wouldn't be a bad idea."
"Yes, sir."
"I'll assign some imperial knights to you."
"Sir?"
"Do you object?"
"Not at all."
Ragna instructed the knight order to assign three imperial knights to Yuri.
They were not talkative.
Wearing black helmets, even their faces were hard to make out.
"Nice to meet you."
"Yes."
"Traveling with us won't be a problem, right?"
"No, sir."
"You don't need any extra care, right?"
"Correct."
"You can say more than just 'yes,' can't you?"
"Yes."
"Good. Let's all stay safe out there."
"Yes."
Yuri added ten knights of Briol to the three imperial knights assigned by Ragna.
Fourteen in total, including Yuri, rode out to the ruins.
While Briol's knights chatted away noisily, the three imperial knights remained silent.
"They're like Death Knights…"
Yuri met eyes with Jared.
He shrugged.
They had once encountered a chattering skull in Erich Briol's dungeon.
Of course, that one had talked too much.
"This looks like the entrance."
They soon discovered a structure that seemed to be a door.
"Let's have a look…"
They couldn't figure out how to open it.
Jared fumbled around the door.
"Do we need a key or something?"
"Then there should be a keyhole."
They circled the entire stone structure, inspecting every surface carefully.
The only place that looked like an entrance to the ruins was the door they had first discovered.
Yuri led the knights back to that spot.
"How do we open it? Do any of you know anything?"
"I don't, sir."
"Really?"
Yuri placed his hand on the door again. Just in case, he raised his mana method, ready to break it down if necessary.
There was a reaction.
"Huh?"
The moment Yuri activated the mana method, a faint light flowed across the door as if it had been supplied with fuel. Then the door vibrated.
And slowly slid open to the side.
"It's open."
Everyone looked at Yuri.
"What did you do?"
"I didn't do anything."
Beyond the door, thick darkness awaited. The stench of a sealed chamber, one long deprived of air, seeped out.
As the door fully opened, the trapped darkness spilled outward, and the interior began to come into view.
A long corridor extended from the entrance.
The inner walls were made of the same stone as the exterior, but they were smoothed so perfectly that they looked like polished marble.
"Let's go."
Yuri stepped in first.
The knights tried to stop him, but he moved so quickly that they scrambled to catch up.
"It's dangerous. You shouldn't be in the front, Your Highness."
"It's fine."
Yuri quickened his pace so they couldn't intervene.
"It's dark."
They hadn't brought torches.
He could barely see by enhancing his vision with the mana method, but it was still uncomfortable.
Yuri glanced around.
There were lamp-like fixtures installed at regular intervals along the walls, but they seemed to have long since lost their light from years of neglect.
He suddenly remembered when the door had opened.
Injecting mana had activated it.
Yuri grabbed one of the protruding handles on the wall.
"Your Highness?"
As he activated the mana method, his mana was absorbed as if being soaked into a sponge.
"This is… unbelievable."
The lights turned on.
Not only that—there was a whirring sound, and the air began to circulate. He could feel wind flowing in and out, ventilating the space.
"What did you just do?"
Laurent asked, and Yuri replied.
"Well…"
He glanced briefly at the three knights from the Empire.
"I don't know. It just worked."
Yuri lied.
Even though he had a good relationship with Ragna, the Empire was still likely to become an enemy one day.
He had no intention of sharing information with such a potential threat.
"Maybe it recognized a visitor?"
"That's possible."
Laurent quickly nodded, catching on. The three imperial knights silently followed behind as before.
"Let's go inside."
Yuri inspected the interior.
At first, the space seemed completely empty, but soon they began to find things.
They discovered a room with a bed and a table.
"Someone used this."
It was clearly a sleeping quarters.
But there were no further traces.
"No clues here."
"Well, it's been buried for a long time. That's to be expected."
"Could this be a remnant of an old kingdom that once stood in the plains?"
"Who knows."
The inside wasn't very spacious. There were several similar rooms, but nothing that could tell them more about the structure's origins.
"It's all been neatly cleared out."
"Mm…"
The floor they had entered contained only sleeping quarters. It felt more like a humble inn.
"Well then…"
Yuri looked up.
"Shall we head down?"
At his words, everyone looked toward the end of the corridor.
There, a passage led underground.
There were stairs, but beyond that point, the darkness was unnaturally thick.
A sense of foreboding crept in.
"Let's hurry. We'll finish exploring before the main unit arrives."
Yuri spoke as if shaking off his unease.
This wasn't the kind of place where danger was likely. And even if it was, there were enough knights with him to deal with it.
Yuri took the lead and descended the stairs.
The darkness clung to his body as if it had form. The farther down he went, the more a strange sensation—like being caught in cobwebs—clung to him.
Then, something caught his foot.
He couldn't see it in the dark.
Yuri felt along the wall, searching for the same lighting device he had found upstairs, and infused it with mana.
The lights turned on.
"This is…"
Bones were everywhere.
Countless bleached skeletons were piled high, with rusted weapons and armor strewn among them.
It looked like a battle had taken place long ago.
Beyond the mountain of corpses, a door made of iron stood firmly shut. A single skeleton sat slumped against it.
It was different from the others.
Yuri realized why.
"A human."
All the other scattered remains were orc bones.
Had the battle between humans and orcs been raging even back then?
Yuri stepped forward and stood before the human corpse.
The bones were scarred in multiple places.
It was easy to imagine how terrible the bloodbath must have been at the time of death.
The skeleton looked as if it had died defending the iron door.
Yuri placed his hand on the doorknob above its head.
No matter how hard he pulled, it wouldn't budge. Even injecting mana yielded no response.
"It's completely locked."
The moment Yuri pulled his hand away—
A burst of light shot out from the crack in the door.
"Your Highness!"
Yuri's body was engulfed in light.
The slumped skeleton also began to glow white-hot.
Yuri instinctively grabbed Guilty and stepped back, but he couldn't move any farther.
"Wha…"
The door opened.
Beyond it loomed a vast abyss of darkness.
In that moment, the entire space around Yuri began to get sucked into the door.
He couldn't resist and was swept up by the flow.
***
Yuri opened his eyes.
He didn't understand the situation right away. Sitting up, he tried to recall what had happened before he lost consciousness.
He had gone down the passage beneath the ruins, opened the iron door, and been thrown inside.
"So this is the interior…"
A faint light floated above his head, so it wasn't completely dark.
Looking back, he saw that the same iron door from before was closed shut.
Yuri knocked on it.
"Hey!"
But there was no response.
He couldn't hear anything from beyond the door.
It appeared he was completely sealed in, likely by magical isolation.
"What is this place…"
The time he had fallen into Erich Briol's dungeon flashed through his mind.
Resting his hand on Guilty, he stepped further inside.
There had been many people, but only he had entered. Why was he the only one who passed through the door?
He soon found the reason.
"This is…"
He felt something vibrating from within his coat and pulled it out.
The red gem that had driven orcs into a frenzy was glowing brightly, hovering in the air.