The room fell into a heavy silence as the three of them tried to digest what Lucus had just revealed.
Natural mana stones.
It was something so rare and unpredictable that even mentioning it brought a sense of awe. These stones could appear anywhere in the world, at any time, without warning or pattern. There was no known way to track their appearance—not even with advanced detection magic. To think that such rare stones were forming naturally around Lucus's mansion of all places...
"Damn, that guy's really lucky," Shirou thought, glancing at Lucus with a mix of envy and curiosity.
Lucus stood up slowly, brushing the creases from his clothes. "The rest of the details will be explained by Darwin. I'll take my leave for now," he said calmly, then walked away into the hallway, disappearing behind the large wooden doors of the estate.
Another short silence followed.
Then, Elliot leaned forward, a thoughtful frown on his face. "Wait. If we're talking about mana stones, then why is this still listed as a D-rank mission? That doesn't make sense."
Darwin, who had been sipping tea quietly, smiled at the question. "Sharp. The reason is simple. Nobody outside this room knows that mana stones are forming here. Not even you three noticed it until Lucus told you."
"The plants around the mansion act as a cover," Shirou added, his voice low with realisation.
"Exactly," Darwin nodded. "The mana stones store a dense amount of mana inside them. But unless there's an outside influence—like a spell or direct contact—they don't release much energy into the air. That makes them nearly impossible to detect under normal circumstances."
Elliot crossed his arms and leaned back. "The plants in the field also emit mana. So, the mana stones blend in perfectly with them. That's smart."
"You're right," Darwin confirmed. "And to answer your question again, this mission is kept at D-rank because it would draw too much attention otherwise. Only a few high-level officials even know about this."
He reached into his coat and pulled out three folded papers, placing them gently on the table in front of them.
"And we'd like to keep it that way. So if you may…"
The three of them picked up the papers and unfolded them. It was a non-disclosure agreement. The contents were strict—none of them were allowed to speak about what they had learned here, not even to fellow adventurers or guild members. The penalty for breaking the agreement was severe: a heavy fine and potential imprisonment, depending on the situation.
After scanning through the document, Amelia and Elliot placed the papers back onto the table, both nodding silently. Shirou stared at them, confused.
Darwin noticed his puzzled look and said, "You just have to infuse a little of your mana into the paper. That will bind the contract."
Shirou raised an eyebrow, but followed the instruction. He channelled a small amount of his mana into the paper, and the runes across its surface glowed briefly.
"Is that enough?" he asked.
"Yes, of course," Darwin replied. "Even though everyone uses mana, each person's mana signature is slightly different. That difference is enough to prove that the contract was accepted by you specifically."
"Oh. I see," Shirou said, nodding. He placed the paper on the table alongside the others.
Darwin gathered the contracts and placed them back inside his coat.
Shirou looked up, a thought occurring to him. "If this is supposed to be a secret, then how did the information leak?"
Darwin sighed and leaned back in his chair. "We have a small team of workers who help us with collecting the mana stones. Every single one of them is also under the same contract you just signed. But... one of them got greedy. He sold the information to a gang of thugs. They broke in once already and stole a few stones from the field."
Shirou's eyes narrowed. "But since the mana stones blend in with the plants, wouldn't it be hard to find them?"
"It would," Darwin agreed. "If not for specialised mana detection devices, even we wouldn't be able to find the stones easily. The field is vast, and without the devices, it would be like searching for a needle in a haystack."
Elliot spoke next, thoughtful as always. "Since the stones don't form frequently, I'm guessing you aren't transporting them every day. You're probably storing them somewhere until there's enough to make a proper shipment."
Darwin looked impressed. "That's correct. We have a hidden chamber within the mansion, and only a few trusted employees know its exact location. It's shielded against detection magic and physical intrusion, but even so, if someone had enough time, they might eventually find it."
He sighed again, rubbing his forehead. "Last time, those thugs managed to get inside the house and made a mess of the place. If the local officers hadn't arrived in time, things could've gone very bad. They did manage to steal a few stones from the field, though."
"And they didn't try to attack you directly?" Shirou asked, surprised.
"They did," Darwin said grimly. "We lost a few guards. It was chaos. We barely made it to Lord Lucus's private chamber in time. Thankfully, it's protected by a high-level defence barrier. If not for that, we probably wouldn't be here talking to you now."
Shirou frowned. "Why not just assign a powerful guard? Maybe someone at the Adept or even Ascendant level? This is one of the most valuable resources in the world we're talking about."
Darwin nodded. "You're absolutely right. But like I said earlier, the existence of these mana stones is a closely guarded secret. If we suddenly bring in a high-level fighter, people might get suspicious. Especially because the mana stones only started appearing here about six months ago."
"Only six months?" Shirou thought again. "Seriously, this guy's insanely lucky."
Darwin continued, "After the first attack, we started considering more serious protection. We've already submitted requests for Ascendant-level guards, but getting someone that strong to act as a simple guard is difficult. Most of them are too expensive, too busy, or just not interested. Still, we're working on it."
The three of them nodded slowly, understanding the delicate balance of secrecy and security.
"That's pretty much all there is to know," Darwin said, looking around the room. "Do you have any more questions?"
Shirou, Elliot, and Amelia exchanged glances.
"No. This is fine," Amelia said, standing up.
Darwin called out, "Come."
A moment later, a female staff member stepped into the room with a polite bow.
"She'll guide you to your rooms. Each of you will be assigned a personal attendant. If you need anything, don't hesitate to ask," Darwin said.
"That's already more than enough," Elliot replied, smiling.
With that, the three of them followed the staff member down the hall, leaving the room behind as the hidden weight of their mission began to settle in.