The thunderclap bombardment brought the Duel to its end, and the Duel Arena ceased its movement.
As the Paradox Brothers' Life Points hit zero and their agonized cries echoed across the space, their projection vanished.
Then—BOOM!—A deep thud resounded as the hidden gate at the end of the labyrinth opened.
Aisha exclaimed, "Does that mean we cleared it? Ya☆Da☆Ze!"
The Duel Arena shut down, and all cards on the field returned to their respective Decks.
However, after the battle, both Aisha and Kevin found a new card added to their Extra Decks:
The destiny fusion—[Archfiend Black Skull Dragon].
Even though it appeared in both their Extra Decks, based on the current conditions of the Fusion requirements, neither could summon it alone if separated.
So Miles wasn't sure whether to be happy about receiving the card or not.
Regardless of his complicated feelings, Nia was beyond thrilled—hopping around in pure joy.
The successful Fusion Summon of Archfiend Black Skull Dragon had deeply satisfied her. For a card junkie, the XP of that moment was like a soul-deck clinging to life and turning the tide—enough to stay high all day.
"Congrats, Kevin. As of now, you've officially leveled up from a club trainee to a full-fledged member."
Archfiend Black Skull Dragon was Level 9—just meeting the entry requirement for the High-Level Spirit Research Society.
But for Kevin, becoming a formal member didn't matter.
What mattered was that this was the strongest dragon born from his destined fusion with Aisha Carlos.
Carefully placing the card into his deck box, Miles hopped down from the rickety platform—which rises during the Duel but doesn't lower back down afterward—using Aisha's not-so-long legs.
"Anyway, let's keep moving. I want to see where this Dystopia card is actually guiding us."
Just as expected, after the hidden gate opened, the black beam of light from the Dystopia card's seal continued to stretch forward.
This underground space had long since surpassed their understanding of its scale. Even if it expanded a few more layers or transitioned through wildly different chamber types, Miles wouldn't be surprised.
Yet, just as that thought formed, the space seemed to defy expectations—the endless sprawl came to a stop.
The final chamber, completely enclosed except for the entrance, had golden-hued stone bricks evoking an aura of ancient ruins.
Most importantly, once Miles stepped inside, the guiding light from the Dystopia card flickered out entirely.
That must mean they'd reached their destination.
In the center of the ruin-like room stood a single item—impossible to miss due to its prominent placement.
A golden ornament shaped like a key.
Miles blinked. "Is that… the Millennium Key?"
Even with only vague memories, he was sure he wouldn't mistake one of the seven Millennium Items.
For one of the Millennium Items to be here—deep beneath Fusion Academy?
Whatever secrets Fusion Academy held… they were more complex than Miles had imagined.
"The Millennium Key? Aisha Carlos, do you recognize this?" Rovik asked. "If it's a key, then it must open a door of some kind, right?"
Yet no matter how carefully Rovik searched, he couldn't find any doors other than the entrance in this sealed room.
"The Millennium Key… I think it's…" Miles narrowed Aisha's green eyes, trying to remember.
"Heehee, you're half right. The Millennium Key does open doors—but not physical ones. It opens the door to the heart~"
Just as Miles was lost in thought, a youthful voice—boyish, clear—echoed from the Millennium Key.
"Who's there?!" All four of them instinctively stepped back, retreating in perfect sync away from the talking Key.
"No need to be so tense. It's been years since anyone's come here. Looks like the first layer of Dystopia's seal has finally been lifted."
A rainbow-colored energy gathered, even more lifelike than the Duel Arena projections. A cute green-haired boy in a hoodie materialized near the Millennium Key and reached out to pick it up.
He smiled politely. "Nice to meet you. I'm the current holder of the Millennium Key. You can call me Camille."
A young boy, looking no older than seven or eight—maybe even younger.
It struck Miles that the Millennium Items always ended up with people like Aisha, Luca, and now this boy Camille…
He started to wonder if this was really a coincidence—or if the Millennium Items had specific preferences.
"Camille, huh? Sounds like a girl's name. So cute," Nia blurted out.
"Heehee, I get that a lot."
With a bright grin, Camille's innocent tone and demeanor radiated zero malice.
"Wait, Camille… are you living in this underground space?" Kevin asked in surprise. It would've been one thing if Camille was just another projection like the Paradox Brothers.
That said, Camille, despite his sudden appearance, felt very real—utterly unlike any illusion.
"More accurately, I live inside the Millennium Key," Camille said. "I'm not fond of the outside world, so I asked Fusion Academy's headmaster to build me this underground chamber. Hmm… I think that was about ten years ago."
"Ten years ago?" Miles echoed.
This tiny boy—who didn't even look ten years old—had already been here with the Millennium Key for a decade?
Then again, anyone who lives in a Millennium Item was probably not exactly human.
Most likely, he was like Miles.
"Camille, are you a spirit residing inside the Millennium Key?"
"Oh? You know about spirit possession?"
Camille's gaze shifted to the Millennium Puzzle hanging at Aisha's chest, and he nodded knowingly.
"Ah, so you are too. Sigh… I guess Millennium Item holders really are fated to be drawn together."
"So Camille, if you're a spirit of the Item, then… what about your host?" Miles asked the most pressing question on his mind.
Could he one day be like Camille—own a real body and leave the Puzzle behind?
"My host, huh… hmm…"
Camille scratched his head awkwardly. After hesitating, he finally said:
"He was probably killed by another Millennium Item holder about twelve years ago."
...
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