Deep within the Demon King's Castle, buried countless levels underground, lay an exceptionally vast treasure vault.
"Isn't this concrete?"
Eiji couldn't help but comment as he observed the vault's exterior.
Unlike the stone bricks and mineral materials used for the outer castle walls, this chamber was constructed with modern reinforced concrete. While its security was undoubtedly enhanced, the aesthetic was completely different.
"Concrete?"
"Just talking to myself, don't mind me."
Eiji recalled what the Demon King had mentioned earlier. It seemed this world had quite a few reincarnators from Japan, who might have brought many Japanese products with them. The presence of such modern elements made sense now.
Airi looked puzzled, but since Eiji didn't elaborate, she didn't press further.
"What's this?"
Eiji approached the vault's entrance, his expression turning peculiar.
"This vault doesn't use an ordinary lock or a magical one, but a rather peculiar combination lock. Only members of the Demon King's lineage know the password."
Airi stepped forward and placed her hand on the combination lock by the door. She subtly blocked Eiji's view as she quickly entered the code.
"Done!"
With a clunk, the vault door swung open like the entrance to a heavy machinery room.
Eiji glanced at the combination lock.
"I will always love Mikami Yua, Asakura Kirara, Takizawa Rora, Momotani Erika..."
Followed by a long string of names.
It seemed the lock used a Romanji-to-Hiragana input method, requiring the exact sequence of names to open the door.
"Where did this password come from?"
"It's been passed down through generations."
Confident that Eiji couldn't possibly decipher the conversion pattern, Airi showed no wariness.
"By the way, your Demon King lineage is surnamed Yasaka, right?"
"Correct. My father is Kyoichi Yasaka, and I'm Airi Yasaka."
"I see, Yasaka the Witch."
"Hey!"
Ignoring Airi's glare, Eiji had already pieced together the logic.
A reincarnator from Japan became the Demon King, built the treasure vault of the Demon King's Castle, and thus left behind a password consisting of this long string of names—names only a select few would recognize. Even fellow reincarnators wouldn't know the exact order.
The former Demon King Kyoichi Yasaka and the witch Airi Yasaka were direct descendants of that reincarnator Demon King, which was why they knew the correct way to open the vault.
After the door opened, Eiji followed Airi inside the treasure vault.
Airi fumbled around for a moment before a bright fluorescent light suddenly illuminated the entire vault.
"Even electricity?"
Eiji muttered under his breath.
The vault was enormous, spanning at least a hundred meters in diameter. Countless treasures lay within, many covered in dust but still emanating waves of magical energy.
Eiji scanned the surroundings, his gaze sweeping over the numerous artifacts before finally settling on a shield placed alone in a display case.
The silver-white shield, styled similarly to those used by knights for charging, looked incredibly ornate and visually striking.
"Is that the divine artifact?"
Though phrased as a question, Eiji's tone was utterly certain. By any measure, that shield's "cool factor" far surpassed the other treasures.
"Yes."
Airi pursed her lips. Though reluctant to hand over the vault's only divine artifact, she still took the initiative to explain its origins.
"The Aegis Shield—forged entirely from the hardest metal, orichalcum. Its defensive capabilities are unmatched. Even humanity's most powerful attack, the Explosion spell, cannot shatter it!"
Huh.
Orichalcum again.
"Orichalcum's prestige is high no matter where you go," Eiji muttered under his breath, then quietly focused his senses.
He had a technique that compared his own deformation speed to that of metal, rendering his body impervious to blades and arrows. Conversely, by using this technique, he could gauge a metal's strength based on the rate of mana consumption.
"Both types of orichalcum are about equally hard."
Eiji nodded in understanding.
"In that case, I don't need this shield. That armor set will suffice."
"No, no, no! What armor could possibly compare to the Aegis Shield made of orichalcum?"
Airi clearly didn't believe him.
"The only thing that could rival the Aegis Shield in defense is the legendary Aegis Armor, its counterpart—also forged entirely from pure orichalcum without a single impurity. No magic or skill can penetrate it..."
Though she was secretly thrilled Eiji didn't want the shield, if she couldn't win him over, she wouldn't be able to reclaim the Demon King's throne.
For the sake of the Demon King's seat, some sacrifices were necessary!
"My armor is made of pure orichalcum."
Eiji waved his hand, declining the eager witch's offer.
"...That armor is made of pure orichalcum?"
Airi froze in place.
For a moment, she doubted her ears were working.
"Yeah."
Eiji nodded calmly.
Back in the Danmachi world, after the artificial labyrinth was mostly destroyed by the evil dragon, the orichalcum gates became ownerless. Some were confiscated by the guild, while others were distributed to various familias as rewards for the operation.
As the one who contributed most to defeating the evil dragon, Eiji received a sizable portion of orichalcum.
He sought out Miss Tsubaki of the Hephaestus Familia and commissioned her to forge a full set of pure orichalcum equipment.
The project reportedly took the entire familia several days, with dozens of high-ranking blacksmiths putting aside all other work—even the goddess Hephaestus participated. The result was the gleaming silver armor Eiji wore, complete with helmet, pauldrons, breastplate, gauntlets, greaves, and more.
With divine craftsmanship involved, this armor was undoubtedly of divine artifact caliber. Its defensive capabilities surely matched the so-called Aegis Armor, making the Aegis Shield utterly redundant.
Airi fell silent.
They had no idea about this.
Because when facing them, Eiji hadn't even needed to defend—he defeated them all through sheer offense.
This meant the Eiji they faced was far from his full power.
This fact weighed heavily on Airi's heart like a barbell.
"Under no circumstances should I confront this guy head-on!"
Eiji secretly made up her mind.
Whether it was seduction or any other method, she was willing to try everything—except direct confrontation with this guy. That was a future she absolutely wanted to avoid.
That scenario would surely be even more despairing than she imagined!
"What's this?"
Eiji turned her steps and stopped before a shop window.