It was an urgent matter, yet I, Atem, King of Eterna, was the one troubled by its timing. The council meeting had ended anticlimactically — everything depended on Diablo's return. The moment the last official left, the throne room settled into a rare, quiet stillness.
Peace… yes.
Peace was a blessing.
You protect your kingdom fiercely — yet every now and then, even a king deserves a moment of stillness.
And so, I decided to use this brief calm to look for Kurobee.
There had been something weighing on my mind.
I stepped into the workshop. The disciples bowed the moment they saw me — not out of fear, but deep respect. Aten's presence carried gravity, authority, and a quiet regality that no one could ignore.
"Kurobee," I called, my voice firm yet warm. "Are you free at the moment?"
Inside the back room, Kurobee had several blades laid out in front of him, each one gleaming with impeccable craftsmanship. He lifted his head, eyes bright.
"Ohh—Atem-sama. Your timing is impeccable. I have something to report."
I raised a brow. "A report? From you? Then it must be significant."
Kurobee rarely claimed something was worth my personal attention unless the achievement was exceptional. And considering how many ideas I had given him — often in passing — I wondered which one he could possibly mean.
He gestured toward the weapons before him.
"It concerns the mechanism you requested some time ago. It is complete."
A flicker of realization stirred in my thoughts — but I maintained a composed face. A king should not look startled.
"Show me," I said.
Kurobee lifted one of the broadswords. On first inspection, it looked like any extremely refined unique-grade blade — smooth, elegant, perfectly balanced. Yet three tiny circular indentations sat near the base of the blade.
I appraised it internally.
«Analysis: Weapon – Classification: Unique-grade.»
Unique grade. Excellent, but hardly the reason Kurobee looked so thrilled.
"Kurobee," I said calmly, "your craftsmanship always achieves this level. What about this blade elevates it beyond your usual work?"
He chuckled softly — a rare, smug smile touching his lips.
"Have you forgotten, Atem-sama? This is the mechanism you envisioned. At a glance, it appears mundane… but it holds an astonishing secret."
Even Solarys — Sovereign of Wisdom, who resided within my soul, spoke with interest.
«Observation: No magical engraving detected. Yet potential energy signatures fluctuate around the hollow slots.»
Meaning it wasn't just a sword.
Kurobee produced a glowing marble-like core.
My eyes narrowed.
So this is the direction he pursued…
He pressed the core into one of the slots—
«Report: Weapon has evolved — Magic Weapon: Broadsword.»
My lips curved into a rare, approving smile.
"So it can be done," I murmured. "You finally succeeded."
Kurobee pumped his fist triumphantly.
"Exactly! The slotted weapon system you described — equipping magic through cores, not engraving — I have finally completed it!"
I placed a hand on his shoulder — a gesture I reserved only for achievements worthy of Eterna's future.
"You have done extraordinary work, Kurobee."
He burst into a grin. Not the foolish kind Shion often made in Rimuru's old world — no, this was the proud grin of a genuine artisan whose creation had exceeded expectations.
I inspected the blade again.
Ordinary appearance.
Extraordinary potential.
Just as I had envisioned.
Kurobee explained:
There were several known ways to craft magic gear:
• permanent engravings (limited magic, not removable)
• natural evolution through long-term use
• forging with spirit stones
But all of these methods were fixed.
My idea — the idea Kurobee brought to life — was different:
A weapon whose properties change depending on the "magic cores" inserted into its slots.
He called them:
• Spirit Cores
• Magic Marbles
High-purity crystals forged through Kaijin's new condensation method.
Kaijin, Kurobee, and Vesta had all worked together to refine the process.
Then Kurobee continued:
"With these marbles, Atem-sama, we can infuse a weapon with earth, water, fire, or wind spirits. Once equipped, the weapon becomes a magic weapon. And most importantly—"
He lifted three marbles of different colors.
"—their combinations create unpredictable and immense power."
My eyes sharpened.
"Show me."
He inserted two marbles — one fire, one wind.
The blade pulsed violently before settling into an intense, vibrating hum.
"The power increases significantly," Kurobee explained. "Fire feeds wind. Wind feeds fire. Their resonance amplifies each other."
Solarys added:
«Estimation: Output increased by a factor of 3.7 compared to standard enchantment.»
Kurobee nodded.
"But mixing opposites — water and fire — diminishes power. However—"
He inserted:
• one water core
• two fire cores
The blade exploded with light, humming like a barely-contained sun.
"This," Kurobee said proudly, "creates a reaction that increases output tenfold. Not triple — not additive — exponential."
I narrowed my eyes, deeply impressed.
The potential was limitless — but so was the danger.
"This is not to be released carelessly," I said.
"Of course not," Kurobee agreed. "That is why I wanted your judgment, Atem-sama."
Solarys spoke again:
«Suggestion: All experimentation should be conducted within the Labyrinth. Controlled environment. Manageable risk.»
"A sound proposal," I said aloud. "We can use the Labyrinth to test all combinations."
Kurobee nodded vigorously.
But there was more.
He explained the difficulty of crafting multi-slotted weapons:
• Three slots: near impossible — he alone could do it
• Two slots: only Kaijin and a handful of master apprentices could achieve it
• One slot: broader distribution possible
"For now," Kurobee concluded, "we can only guarantee three slots with my full power. But even a single slot blade with the right marble can rival rare-grade magic gear."
"And a three-slot weapon?" I asked.
Kurobee smiled with reverence.
"With the right cores… it can rival legendary weapons."
I let silence fall for a moment.
Then—
"Kurobee," I said, "Eterna will advance because of you."
His face reddened in pride.
I declared the next steps:
• Three-slot slotted weapons → for elite officers of Eterna
• Two-slot weapons → for labyrinth bosses and high-tier rewards
• One-slot weapons → mass production for challengers
• Magic marbles → scattered throughout treasure chests
• A dedicated workshop → to recharge depleted Spirit Cores
Kurobee looked thrilled.
"I will teach my disciples immediately. We will increase production at once."
"Good," I said. "I will entrust this entire project to you."
Kurobee bowed deeply.
"As you command, Atem-sama."
And with that, the future of Eterna's military — and its technological superiority — had begun.
I turned, cloak sweeping behind me like a king stepping away from a completed ritual.
"Continue your work, Kurobee. Eterna's strength will soon surpass all realms."
"Understood!"
And so — I left the matter to Kurobee.
"By the way, Atem-sama. Surely you have something in mind for me if you came all this way, right?"
That was when I remembered. I had completely forgotten the reason why I came to find Kurobee in the first place.
"The thing is, my sword—" I began, taking out my straight sword to show Kurobee.
"Are there finally holes on your blade?"
"No, that's not it. I wouldn't be as surprised if it were just that."
"I suppose you have a point…"
My sword wasn't bent nor shattered, and was completely attuned to my mana. The blade was as black as the midnight sky.
However, nowadays, if I infused my blade with mana—
Shocked, Kurobee stared with his mouth open. "What! The b-blade is turning golden—no, that's not the only color. It's a rainbow. The blade is giving off the glow of a rainbow!"
"Surprising, right? that's why I decided to discuss it with you."
I had been gazing at my sword back in my chambers one day when it suddenly started changing hues. Obviously, I was caught off guard. The blade was giving off a rainbow-like sheen. Gold was never used during the forging process, yet it was giving off a shine brighter than orichalcum. That was why I decided to investigate the matter.
«Answer. This is the "Ultimate Metal" Hihiirokane.»
Solarys, Sovereign of Wisdom, had said that to me. Apparently, it was some very impressive metal that was superior in quality to the orichalcum I refined. Thus, I came to Kurobee for confirmation.
"T-this… what in the world is this? I can't even analyze it…"
"I think it is called something like Hihiirokane?"
"Hihiirokane? D-does something like that really exist? It's said to be a mythical-grade metal that possesses immutable properties. I honestly thought it was something of a fairy tale…"
Kurobee was no longer just excited. He was stunned speechless.
I figured that this change would be powerful, but it seemed to have exceeded my expectations. Afterward, Kurobee and I studied the now Hihiirokane-comprised straight sword together.
In the end, we discovered that this sword would only respond to my mana. Even if Kurobee infused his mana with it, the blade would remain jet black, and the metallic reaction at that point was still magisteel. However, it had indeed transformed into authentic Hihiirokane.
This Hihiirokane seemed capable of resisting the wavelengths of every single physical property. Normally, it wouldn't even reflect light because it simply cancelled out the wavelengths within the visible light spectrum, which probably explained why the blade was pitch black. It could mask its unique properties from others as well—
Only when I imbued it with my mana and entered a state of combat would this sword begin to give off a rainbow-colored shine.
Even though it might be too eye-catching to unsheathe in a public area, as long as I didn't infuse it with my mana, it should masquerade as an innocuous sword well enough. Moreover, it was also far sturdier than most average weapons, or should I say, its immutable properties meant that "It could not be destroyed." Even when it was damaged, it could be repaired by saturating it with mana.
I was curious about what would happen if two Hihiirokane weapons clashed with one another, but I suppose it was no use thinking about something impossible like that.
There was only one thing I could say for certain right now: this straight sword was worthy of being my weapon, and it had evolved to outshine the sturdiness of any other sword in the world. With this sword complementing my 'Absolute Defense,' I could afford to be a bit reckless at times.
In addition—
This sword was not complete just yet. In order to engrave it with a magic marble—magic crystals of different spirit properties—I planned on drilling a hole at the base of the blade so that said marble could be inserted.
I was looking forward to the day that this sword could be finally considered complete. It was already quite impressive, but I couldn't help but feel excited at the thought of its great potential.
"This sword is really something else. Despite the fact that I was the one who made it, the state it is in now is something I could have never imagined…"
"No no no, that's not true at all. Kurobee is super amazing!"
"Thanks for the compliment. I am truly happy to hear Atem-sama's praise like that!"
The special properties of this sword were only possible because Kurobee, while undeniably modest, was the one that made it. That much was certain.
"Even so, I believe that this sword can triumph Hinata's saber."
My sword was Kurobee's greatest masterpiece, so wouldn't it be at least the equivalent of a legendary-grade? I had spoken based on this thought.
Kurobee's answer to my comment was quite unexpected. "Are you referring to the legendary-grade Moonlight Saber? Hmm… Actually, this should be stronger. Perhaps this sword could possibly be a lead-in to the mythical-grade weapon witnessed by Veldora-sama."
Mythical-grade—that was a phrase synonymous with the word "ultimate" and "supreme." There was no such equipment for sale on the market. There was no such record of it in legends and folktales. However, something like that definitely existed.
For instance, Milim's magic sword, Tenma, was certainly one of them. She had shown it to me before. According to Solarys, Sovereign of Wisdom, the quality of Tenma was above that of the Moonlight Saber. This sword had become a precious item like Tenma—I couldn't help but imagine that it had also reached the ultimate realm of mythical-grade.
According to Kurobee, it appeared that my sword, at its present state, was at the level equal to higher-end legendary-grade weapons. In a way, there was a lot to look forward to as it had the potential of reaching mythical-grade quality one day.
We were both mesmerized by the sword for some time.
"Ah ah, it's such a cool sword—"
"Indeed. Such beautiful blade patterns are truly a rare sight."
The immutable Hihiirokane gleamed brightly, adding a beautiful color to the Hamon—demonstrating the very essence of Kurobee's skilled techniques.
We both couldn't contain our excitement while observing the almost art-like patterns of the blade. Its beauty was irresistible; it was the best sword I had ever laid eyes on. And it would also continue to evolve. It wasn't that far of an exaggeration to say that I had already acquired a mythical-grade weapon.
This unexpected discovery made me very happy.