They had been making their way through the Underground Space for about two hours, and naturally enough, some of the Centaurs were growing dissatisfied with pressing on.
Had they been on the surface—on the grassland—running for a couple of hours wouldn't have bothered them in the least. Out on the plains, there was the wind in their faces, the blue sky overhead with its clouds and sun, and on all sides the rich variety of nature: grasses, trees, stones, rivers.
But the Underground Space was different.
Since they were running, they could feel the air against their bodies, but it was just air—not wind.
What wore down the Centaurs' spirits more than anything was the unchanging scenery. No matter how far they ran, everything looked exactly the same.
In reality there were probably subtle variations, but nothing as obvious as the shifting landscapes of the surface grasslands.
Running endlessly through such monotony grew tedious, and a good number turned back midway, returning to the ramp that led above.
...Even so, the majority kept going. They wanted to see the Queen who had tormented them—even if only scraps of flesh, charred remains, or ashes.
Knowing full well how much the Centaurs had suffered at the hands of the Dragonias, Rei couldn't refuse Zai and the others now that they harbored such a wish.
(Yesterday, I would've been able to see the Queen from this distance by now. ...Well, no point in me saying that, considering I'm the one who burned her.)
Gazing into the distance from Set's back, Rei reflected somberly on the previous day's battle.
It had been a genuinely dangerous fight, even for him.
"Rei, what's wrong?"
Asdena, who had been running nearby, looked at him with curiosity. He'd probably noticed Rei staring off into the distance while perched on Set's back.
Rei shook his head to indicate it was nothing.
"Just thinking about yesterday. If we'd been here at this point, the Queen would already have been visible."
"...Hou."
Asdena's expression shifted to one of keen interest. He was no doubt imagining just how massive the Queen must have been if she could be spotted from this distance.
"Dragonias don't use magic, do they? Or did the ones in this Underground Space cast spells or something?"
Dolfina, who had apparently been listening in on their conversation, directed the question at Rei.
Yesterday had been hectic for one reason or another, and there hadn't been a chance to ask about the battle underground in any detail. Today, after waking and eating breakfast, there had been a stretch of downtime—but the timing had been off, and Dolfina had missed his window. After that, he'd never quite found the right moment to ask as they made their way here. Figuring this was his chance, he'd seized on the conversation between Rei and Asdena.
Rei, completely oblivious to Dolfina's circumstances, thought for a moment before answering.
"Right. There were Dragonias with various Special Abilities, but none that used magic."
"Special Abilities? You mean like the Mottled Dragonias?"
"Something like that. Optical Camouflage—an ability to turn transparent. Regeneration that could instantly repair a sliced-up body. Breath attacks. Short-range Teleportation. Walking freely through the air. ...Now that I think about it, they had some extraordinary abilities. And the Queen had her own variety of Special Abilities on top of that."
What had surprised Rei most was the Queen's use of a Regeneration Ability similar to the black-scaled Dragonias'.
It was possible she could use the other Dragonias' abilities too, but fortunately, she never actually deployed them.
...Instead, she'd unleashed countless tentacles with vibrating tips and violently shaken her entire body to boost her defenses, among other things.
(The Queen definitely possessed high intelligence. She could even communicate with us, after all. Though that communication was limited to single words, so we had to translate them ourselves.)
Given the Queen's nature, if she had been able to use other abilities, she would have deployed them during the fight with Rei.
Of course, with a body that massive, Optical Camouflage wouldn't have prevented attacks from landing. The Teleportation ability was fundamentally short-range, so it would have been pointless for something her size. And with that enormous bulk, walking through the air was out of the question.
The powerful leg strength of the transparent-scaled Dragonias was likewise something Rei couldn't see being useful to the Queen.
(That would leave only the white-scaled Dragonias' Breath as something practical.)
As the conversation with Dolfina continued and more time passed, they eventually reached a place where—apparently from the effects of the ground being scorched by extreme heat—the earth had been transformed into glass across a wide area.
"Whoa..."
Who was it that murmured that upon arrival?
...Strangely enough, Rei himself was also stunned by the sight.
When he'd defeated the Queen, his consciousness had already been fading, and he hadn't realized the ground had ended up like this. He'd even tested the performance of Terrain Manipulation after it reached Level 5, yet still hadn't noticed the glassification—which probably proved just how close to his limit he'd been.
(I should have been conscious... but was I really so hazy that I missed this? Though honestly, if it had been like this, I should have noticed. ...Which means maybe it turned out this way after I left?)
If that were the case, then it made perfect sense that he hadn't noticed the glassification while he was still here.
Perhaps unwilling to admit he'd overlooked something so obvious, Rei half-forcibly convinced himself of that explanation.
...Then again, considering what the battle yesterday had been like, no one would think to blame him.
"This is incredible."
While everyone was struck speechless by the glassified ground, the first to snap out of it was Anastasia.
Given her intensely curious nature, expecting her not to be fascinated by glassified ground would have been unreasonable. She immediately slid off the Deer she'd been riding, sprinted toward the glass, and began examining it.
Fana followed suit, dismounting and heading toward the glassified area as if chasing after Anastasia.
"If this were outside, it would reflect the sunlight and look absolutely beautiful," Vihera murmured with a touch of regret.
The ceiling and ground here glowed faintly for some reason, but of course that couldn't compare to sunlight. The light did reflect off the glass, but it didn't look nearly as stunning as it would have outdoors.
"Yeah. ...Still, it's not like I could easily pull something like this off on the surface."
Exactly how much heat was required to turn soil to glass, Rei couldn't say. But back in Japan, he'd once seen a TV special about OOPArts—artifacts that shouldn't exist in ancient civilizations, so-called out-of-place objects—and the Ancient Nuclear War Theory it introduced had shown ground that had been glassified.
In other words, the glassification of this ground meant that when Rei had poured his magic power and life force into the Flame Emperor's Crimson Armor inside the Queen and burned her from within, the temperature must have been comparable.
...Of course, if that much heat had been generated, it wouldn't have been surprising for the entire Underground Space to have been affected. The fact that the damage was limited to this area was probably a testament to the unique nature of the Flame Emperor's Crimson Armor as a skill.
"...Hey, Rei..."
"Anastasia?"
Anastasia, who just moments ago had been examining the glass with intense fascination, turned to look at him with an expression of sheer disbelief—something close to fear.
"You... this is serious."
"Serious?"
Rei found it hard to believe this was the same Anastasia who would throw herself into considerable—no, significant—danger to satisfy her curiosity. He prompted her to continue.
"Yes. I'm an elf, so I'm not particularly knowledgeable about Fire Spirits, which is why it took me a while to notice. But this glass has powerful Fire Spirit energy sealed inside it."
"...A Spirit? Why?"
If she'd simply said it was the power of fire, Rei would have accepted it without question. After all, he had generated tremendous heat through the Flame Emperor's Crimson Armor to burn the Queen. But introducing the element of a Spirit made the question "Why?" only natural.
At the very least, Rei couldn't use Spirit Magic.
(Wait. Spirit Magic? A Spirit... a Spirit, huh. The Queen desired the Spirit Egg—a mass of powerful Earth Spirit energy, for all intents and purposes. In other words, it wouldn't be strange if the Queen herself was a being with some connection to Spirits. And I burned that Queen to death with the Flame Emperor's Crimson Armor. If that's the case...)
Having organized his thoughts that far, Rei looked at the glassified ground again and spoke.
"So it wouldn't be strange for a Fire Spirit to be sealed in the glass...?"
Under normal reasoning, it was plenty strange. But considering the current situation, perhaps—through a truly enormous "perhaps"—such a possibility wasn't out of the question.
...If mages, Spirit Mages, or researchers heard this, they'd likely insist in unison that such a thing was absolutely impossible.
Yet even so, given the circumstances, one could believe it wasn't impossible.
"I don't know why it turned out this way, but it was probably formed by coincidence piling on coincidence, with several more coincidences stacking on top of that."
"...Just how many coincidences were involved, I wonder?"
Anastasia muttered in exasperation, but she herself probably understood that without such an explanation, a situation like this wouldn't exist.
"In any case, this glass might be useful for something, so we should take some back with us."
"...Could it serve as Magic Item material?"
With just a hint—but a definite measure—of hope in his voice, Rei asked Anastasia.
For someone like Rei, who collected Magic Items as a hobby, if this glass could serve as material for some kind of Magic Item, leaving it behind simply wasn't an option.
Glass imbued with the power of a Fire Spirit.
Just imagining what kind of Magic Item it might become and what effects it might produce brought a grin to his face—the battle against the Queen had been worth it.
"Right. I imagine there are all sorts of applications. The specifics would depend on the alchemist. But beyond that, this glass can probably be used as a direct offensive tool as well. ...Watch."
With that, Anastasia picked up a sliver of glass about the size of a fingertip from the glassified ground and threw it toward an empty area some distance away.
The instant the glass touched the ground, it erupted into intense flames.
When Rei heard "glass and fire," what came to mind was a Molotov cocktail. But the blaze generated by the shard Anastasia had thrown dwarfed any Molotov cocktail beyond comparison.
...Of course, the Molotov cocktails Rei knew about were purely from manga, anime, and games—he'd never actually seen one with his own eyes.
"That's... incredible."
Rei murmured, genuinely awed by the flames.
The shard Anastasia had thrown was tiny. Which meant that if a larger fragment were used, just how massive would the fireball be?
Just thinking about it brought a smile to his lips.
"It works as a direct attack and as Magic Item material. ...That's top-grade, without a doubt."
Anastasia nodded at Rei's words—and then raised a question.
"You said your skill caused this, but what kind of skill is it, exactly? As far as I know, no skill exists that would produce something like this."
"Probably not."
Rei acknowledged her point.
Truthfully, he felt he'd pushed himself recklessly in the battle against the Queen. Skills were what those with magic power but no ability to cast magic converted that power into through their own unique techniques or arts—they were, in a sense, infinitely varied. It was fair to say there were as many skills as there were people.
...Naturally, it wasn't unheard of for different individuals to possess similar skills.
Entertaining these thoughts, Rei stored the glass in his Misty Ring.