The man's identity was something even Osian hadn't expected.
"Could it be, you were also a Knight?"
Osian felt something strange while speaking. What dwelled in his eyes was clearly the starlight that Knights wielded, but it was so faint that it seemed like it could extinguish at any moment.
"I was, once."
Osian carefully observed the man's appearance.
The starlight he possessed appeared precariously dim, as if it could go out at any moment.
Above all, what enveloped his festering body was a dark energy that was chilling just to look at.
'Black magic?'
The power felt momentarily was close to black magic. However, it was something even darker and heavier, something that could be called an ancient power.
"Is this explanation sufficient?""I see."
When Osian nodded, the man put the mask he had taken off back on his face.
That action, unlike when first seen, was trembling as if anxious.
*Inhale* *Exhale*
After putting on the mask and steadying his breathing, the man's hand trembling finally stopped as if he was now stable.
After adjusting his mask a few times, he apologized to Osian.
"I apologize for showing you such a repulsive sight."
"I don't think much of it. If someone has their circumstances, there's no reason not to understand that."
"Thank you for saying so."
"More than that, that body. Originally you should have reached your limit by now, but you're alive and not dead?"
Osian asked for his honest impression about the energy emanating from the masked man.
Something similar yet different from black magic. That power was binding the masked man like a curse, but conversely, he couldn't shake the thought that it was thanks to that power that he was alive.
The masked man nodded.
"Since I've already shown you, there's nothing to hide. Yes, that's correct. Whether I should say thanks to this or because of this, I am alive and not dead."
"I suppose asking 'how long' would be a meaningless question."
He must have been alive since before this city was born.
That time would be similar to when Osian was active.
However, for Osian, the masked man wasn't in his memories.
If he had been a Knight, he would have been one of the NPCs, and if they had met, there would have been something that came to mind.
'Even if his skin is rotting and damaged, it's strange that I can't recognize him. Just like when I first met Asmer, my instinctive intuition rather than rational judgment would have recognized him. Moreover, until he took off his mask, I didn't even know he had starlight.'
Rather than being faint, it was presumably because the mask itself had some hidden function.
It was certain just by seeing how he who was suffering when the mask was removed now seemed peaceful again.
"Currently, I am merely close to being a barely living corpse. However, since I have responsibilities to bear, I hold an important position here in Zero Ground."
"Important position. Quite a humble way of putting it."
It must be more than just an important position. Having witnessed the city's birth, he must have had a significant influence in creating this Zero Ground at the very least.
While he might not rule the underground city alone, it was clear that he was at least one of its pillars.
"Come to think of it, I heard from the Underground Keeper on my way here. That this place was one of the first cities that became the origin of Tirna."
"Yes, that's right. Zero Ground is where Ether Water was first discovered in the underground cavern. It's also the first mining site."
"Ether Water..."
Osian recalled the pipeline he had crossed when coming down here underground.
It seems that was the transport pipe that transmitted Ether Water.
"But for such a valuable resource as Ether Water being discovered first here, there doesn't seem to be much known about it, and it doesn't seem to have a very good image."
"Well, that's inevitable. While this is the first, it's not the largest, and now no more Ether Water comes out. No, a very small amount does come out. Just enough for us to barely sustain ourselves."
"So it was abandoned."
"In any case, this is the first city. That's why it's called District 0. And the cities that were built together have District 1 and District 2 respectively."
The masked man raised his finger to point at the ceiling, or more precisely, beyond the ground.
"Thus District 1 is in the sky. District 2 is on the ground. District 0 is underground. That's how Tirna was created with these first three districts."
"District 1 is in the sky?"
"Yes. That should be well-known to those who would know. The floating district Elnirond. It's a huge island floating in the sky. I've never been there, but people who have been say the scenery is quite beautiful."
To the masked man who was speaking casually, Osian asked straightforwardly.
"So, you had some kind of past involvement with that monster, and you want me to resolve it?"
"Yes. However, as I mentioned, what I want is for the monster to return to its original district. Until then, I would appreciate it if you could check and prevent it from causing harm to the surroundings."
"What's in it for me?"
"What do you want?"
Usually when Osian asks this, people would normally say what they could offer.
But the masked man asked in return. Asking what he wanted.
That could be seen as somewhat arrogant. It meant that whatever was wanted, he could provide it all.
Come to think of it, the man before him was a very long-lived being who had witnessed the city's birth.
Although he's now unable to die and living only underground due to some ancient curse, time was something that couldn't be ignored.
If he had held even a small share in the city's past, that would now be something of astronomical value that couldn't be measured.
'But he's not saying that to offer such enormous money. Rather, he's asking because he knows what I want.'
Perhaps it's due to his long-lived experience. He probably knows what Osian wants.
"Information about the fall of the Knights, traces of other Knights, and what has happened until now."
"Would that be sufficient?"
"You're the one underestimating that information too much. Aren't these things that one wouldn't dare find traces of anywhere else but through you?"
"That's true. But that doesn't mean I'm the only one. There are others who know as well."
"At least right now, you're the only one in front of me."
"Haha. In that case, I'll take it that you accept the request."
Osian brushed his hand over the sword at his waist.
The masked man stared intently at Osian's sword.
The gaze seemed to linger particularly long.
"Do you miss it?"
To Osian's question that implied many things, the masked man shook his head.
"It left my side long ago. I was just feeling nostalgic."
"For something like that, you seem to have strange lingering attachments."
Osian shrugged his shoulders and stood up from his seat.
"I'll accept the request."
"I pray for your success in battle."
Success in battle.
Back then, he had said similar words.
He had wondered why such an old-fashioned word was used, but now he could clearly understand.
"Don't worry. The sword is with me."
*
"This is crazy. We're really working with those surface dwellers?"
"The opponent is that crazy monster. Besides, don't look down on surface dwellers. They're actually skilled."
"Tch. They're still surface dwellers. Who knows when those detestable ones will stab us in the back?"
The underground residents held considerable dissatisfaction with the fact that surface people, including Adela, would be moving together with them.
But it was just talk among themselves, they didn't openly pick fights.
They also understood well the gravity of the situation, and since the higher-ups had said so, they couldn't refuse.
"Still, the reaction isn't as bad as we worried. Though the atmosphere isn't very good."
That was what Adela said to Osian after observing the residents' reactions.
"They know what's important too, they won't do anything strange. Especially with the Underground Keepers involved. We just need to do our job."
"Yes. Thanks to Mr. Osian negotiating well inside. By the way, who exactly did you meet? They seem to be no ordinary high-ranking person in Zero Ground."
"Just...an old colleague."
Adela found that answer even more confusing.
"An old colleague? Were you perhaps from underground?"
"Not exactly. Let's stop the chat here. We're starting now."
Adela couldn't ask her remaining questions because the Slithering Sisters were approaching Osian.
"The monster's location has been confirmed."
Everyone listened to Atilla's words.
An Underground Keeper brought a map and spread it wide.
Over the complex map of the underground waterways, the Underground Keeper pointed without hesitation.
"Here. Currently it's residing in D-35. It's moving from here to D-23 now. It encountered some criminals who were hiding during its movement, and they were all torn apart and killed by it."
"What do we need to do?"
Answering Hammond's question was the Underground Keeper who had some friction with Osian earlier.
"The monster's dwelling is in the B-3 sector. It's currently filled with water so we're draining it. It'll take about 30 minutes. Until then, we need to guide that monster to go to the B-3 sector."
"That monster? Does someone need to be bait with meat or something?"
"Something like that. First, we plan to lower the bulkheads of passages where the monster might roam. We need to prevent it from escaping to other paths."
One of the mechanical arms that had been repaired revealed a pen tip from its index finger and began marking the map.
Black ink X marks were made on passages where the monster might escape to.
"All bulkheads must be operated manually. It's not that difficult. Three people are enough."
"Even so, the number of bulkheads to lower exceeds thirty."
"Right. Even if done sequentially, we need at least 60 people minimum. Plus, we need to pick only those with quick feet. If you work leisurely and get caught by the monster that senses your presence, no one can take responsibility."
"This is the important part."
Krua pointed at the current D-35 sector where the monster resided while speaking.
"While the rest close off the passages, we need to guide this monster to come to the B-3 sector."
"How exactly do we guide it?"
Answering Adela's question was her younger sister Atilla.
"T-that... We use the most simple and intuitive method. Since that monster is hostile to all living things..."
"Hostile to all living things, does that mean using people as bait?"
"F-first, I can guide about half with my summons somehow. But since my power isn't infinite, after that, someone else will have to do it directly."
Silence hung over the gathering at those words.
The question was who would take on the dangerous role of attracting the monster's attention and guiding it to its dwelling.
"I'll take that on."
People's gazes naturally turned to Osian.
Adela asked with a worried voice.
"Are you really okay with this?"
"Hey. Miss Civil Servant. You don't need to worry unnecessarily."
Krua stepped in to defend Osian instead.
The people here didn't know, but she was someone who had directly witnessed Osian engaging in combat with that monster.
She knew at least that Osian hadn't answered out of bravado.
"We've set up backup plans just in case, but let's hope we don't need anything more."
The Underground Keeper's words put a period on the meeting.
The operation began and everyone dispersed to carry out their assigned roles.
Though closing the bulkheads wasn't related to combat, it wasn't entirely safe either.
In the underground waterways, danger wasn't just that one monster but no one could voice complaints because the one going to face the monster, which could be called the greatest danger, was none other than Osian.
Of course, he won't go alone.
He was planned to move as a team of four with Krua and Atilla and one Underground Keeper.
"We should go too."
Unlike her usual self, tension was evident in Krua's voice.
The Underground Keeper assigned with them was a young man with a sharp impression. The reason he was chosen was because he was the fastest among the Underground Keepers.
"If you fall behind because you're slow, I won't take responsibility so keep up quick."
He moved, while Krua, Atilla and Osian followed behind.
Atilla mumbled something while running.
At the same time, eel-like creatures rushed out from under her baggy skirt and swam somewhere along the waterway.
And after some time had passed.
Thud! Thud! Thud!
Along with the sound of bulkheads closing.
-Aaaaaaargh!!!
The monster's tearing scream echoed through from beyond the passage.