Bell Fougma, the Sun Castle's Chief Assistant to the Lord, sat with her head buried in her hands.
Ever since she had been assigned her duties, she had been sequestered deep within the heart of the Sun Castle. Consequently, she had been left completely in the dark regarding the outside world.
She hadn't known that the Sun Castle had been occupied by the Devil Race, nor that Kuzuden was now acting as the Castle Lord. She hadn't known that monsters and magic beasts were running rampant, or that the majority of the castle’s facilities had fallen into ruin. Most importantly, she hadn't known that the Sun Castle's fuel was almost entirely depleted, causing nearly all of its functions to fail.
"I do not mind a new ruler or a new Castle Lord. However, I am on the verge of a breakdown over the fact that not a single person thought to consult me."
"Consulting you while you were in total isolation would have been impossible, Bell," a voice replied.
The one Bell was complaining to was the Sun Castle Crystal Stone. This crystal actually had a proper name: Gou Fougma. Bell had introduced him to me. Based on their names, I assumed they were siblings of a sort.
I was told they were artificial lifeforms created specifically to assist the Lord of the Sun Castle. Including Bell and Gou, sixteen units had originally been manufactured. While all sixteen still existed, only Bell and Gou were currently active. The others had entered a state of suspended animation due to the castle’s critical fuel shortage. Even Gou's current form as a crystal was a measure intended to conserve energy.
"How did the fuel shortage become this severe?" Bell demanded. "With the original planned stockpiles, we should have been able to remain airborne for five thousand years."
"Ah... well... do you really want to know?" Gou asked.
"By all means."
"This castle was originally built as a sort of lavish villa by a human king who poured a fortune into it, right?"
"Indeed. We were created during that era for management purposes."
"And then that king became obsessed with a prophecy, gave you your role, and locked you away in isolation."
"Just remembering it infuriates me."
"Well, about twenty years after that, the king passed away, and a succession struggle broke out. Ownership of the castle eventually fell into the hands of a certain hedonistic noble."
"How tragic."
"That playboy noble ran into financial trouble and sold off the Sun Castle’s entire fuel reserve..."
"What?"
"Even that wasn't enough to cover his debts. Eventually, he sold the castle itself to the God-kin... ah, the Angel Race. Bell, you have to call them the Angel Race now or they’ll get angry."
"I understand, just continue."
"The castle was sold to the Angels. Afterward, they remodeled it for combat. They replenished the fuel, but they used it all up powering their armaments. When the Demon Race launched a counterattack and sent monsters into the castle, the very last fuel depot was targeted and destroyed. It was a total loss. Since then, we’ve been scraping by on whatever fuel was left in the internal systems to reach the present day."
"I see. So, I assume that playboy noble was beaten to death centuries ago?"
"Unfortunately, no. After selling the castle, he lived a life of luxury for another fifty years and died peacefully in his bed, surrounded by his grandchildren."
"Fine. I shall curse him. Give me his name and the details of his descendants."
"The descendants have nothing to do with this, so please stop."
Gou tried his best to soothe the rampaging Bell. While watching that scene unfold, the rest of us enjoyed a meal prepared with ingredients Rusty had brought over.
I had been wondering if there was a way to make the Dungeon Potatoes grown here taste better, so I tried tossing them into a curry. As it turned out, curry truly is a miracle food. It completely masked the unpleasant flavor. The texture remained firm, so they might be useful for bulking up a meal, but I didn't see myself going out of my way to cultivate Dungeon Potatoes back home.
Still, the Devil Race had survived on these alone for generations, so the nutritional value had to be high. Since they were potatoes, I wondered if they could be turned into sake. Even if they could, the taste would be the deciding factor. If a decent liquor could be made from them, they might actually have some value.
This, of course, assumed that Kuzuden and his people intended to stay here and keep farming them.
"Kuzuden, what are your plans for the future?" I asked him while he was enjoying his curry.
"Ah, yes. I’ve discussed it with everyone, and if possible, we would like to continue living here."
Apparently, a few of them planned to head out to see if any of their kin back home had survived, but they intended to return afterward.
"We've spent five hundred years here, after all. Though, I’ve personally only been here for about thirty."
"Does that apply to the Dream Demons as well?"
"Yes. We’ve established a stable life together."
I see. If they were staying of their own volition and not out of obligation, then there was no issue. However, that brought up another problem.
Bell stepped toward me to voice my own growing concern.
"Based on my calculations of the remaining reserves, the Sun Castle will be unable to remain airborne in about three years."
Kuzuden panicked at her words. It was a natural reaction; their home was literally about to fall out of the sky.
"If it can't fly, then it can't be helped," I suggested. "Why not find a place to land it on the ground?"
"The ground?" Kuzuden’s gaze drifted toward Kuro's offspring. "If we descend to the surface, we’ll just be overrun by monsters and magic beasts again."
The Sun Castle’s primary defense was the fact that it stayed in the air. That made sense. But then it hit me.
"If it's just a fuel shortage, why don't we just buy more?"
It was a simple oversight. If you run out of gas, you just need a refill. Kuzuden seemed to agree with the idea, but Bell shook her head.
"The Sun Castle's fuel is refined from a rare mineral. It isn't something that can be easily obtained."
"Is that so?"
"Yes. It is called Sun Stone. It is a rare mineral that constantly emits heat, and we require mountains of it."
If it was a rare material, we might be in trouble. Then again, I could always ask the Demon King, Progenitor-san, or Dos if they had any leads.
"Hey, can I have a word?" Lu poked me while I was deep in thought.
"What is it?"
"She’s talking about Heat Retention Stones."
"Huh?"
"They used to be rare, but then a massive vein was discovered and the price bottomed out. They're common now."
I looked over at Bell. Her face was bright red. I suppose it couldn't be helped, given how long she had been isolated. We would just have to catch her up on everything.
If she meant Heat Retention Stones, those could be mined at the Hot Spring Area. If I asked Michael-san, we could probably secure a significant amount. I pulled out one of the Heat Retention Stones I carried as a hand warmer and showed it to her to confirm.
"For now, how much do you need?"
"To start with... about ten kilograms would suffice."
If that was all they needed, it would be faster to just go dig them up at the Hot Spring Area ourselves.
"You can completely control the navigation of the Sun Castle, right?"
"Yes."
"Then, let's head north. Do you have a map?"
In response to my request, Bell waved her hands, and a high-tech projection of the landscape appeared on the floor. While some parts of the projection were still showing as fields, the general topography was clear.
We decided that the Sun Castle would head toward the Hot Spring Area. I had considered having Hakuren and the others transport the stones, but it was better to minimize the distance the castle had to fly on its current reserves.
At that moment, Kuzuden formally offered his allegiance to the Village of the Great Tree.
"We were in the middle of discussing our future, but... it seems it would be difficult for us to restore this place on our own. Lord Sun Castle—I mean, Lord Gou—has also agreed that this is the best course of action."
"It is safer to belong to a territory than to be a castle of drifters," Bell added.
To be blunt, they admitted they had no way to pay for the Heat Retention Stones and were throwing themselves on our mercy. In exchange, they offered to hand over all the ancient technology and items remaining within the castle.
I wanted to give them an answer on the spot, but I needed to take the proposal back to the village and consult with the residents first.
"We look forward to your answer," Kuzuden said, bowing.
Bell bowed alongside him. Gou was still a crystal and couldn't bow physically, but I could feel his sincerity nonetheless. I decided I would do my best to bring them back a favorable response.