In this world, all 41 members of Ainz Ooal Gown have crossed over into the One Piece world.
But they all arrived at different times than Ainz.
Ainz himself arrived 800 years later.
By the time he showed up, the history of the other 40 members had been almost completely erased by the World Government and Imu.
The only record of their existence lay within the Poneglyphs because, well, they were powerful, chuuni nerds who wanted to make sure history remembered them.
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The Ancient Weapons:
In this version of history, the legendary Ancient Weapons have a completely different origin.
Uranus: One of the twenty, a World Item that is capable of controlling the weather.
Pluton: It was created by one of the supreme beings, a sci-fi-based genius, with help from others. The ultimate doomsday weapon.
Poseidon: It is one of the 40 Supreme Beings, a Fish-Man Beast King. The Fish-Men are his descendants. Shirahoshi awakened his bloodline. The Sea Kings are descendants of his pets. Noah was built at his command.
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Other Key Modifications to the One Piece World
Zunesha: It is familiar of one of the 40 Supreme Beings and its strength is easily Admiral-tier or beyond.
Wano: It was one of the guild members personal territories—because of course, a place full of samurai would attract chuuni overlords.
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The Fall of the Great Kingdom
800 years ago, the world was a unified kingdom. The D. Clan ruled as its royal family.
A group of ambitious conspirators, including the Five Elders, plotted to overthrow it.
But they lacked the power—until forty overpowered isekai warriors conveniently appeared out of nowhere.
With a little manipulation and some clever lies.... the 40 helped destroy the Great Kingdom.
(Imagine fighting at least 40 Admiral-level beings and some even beyond Yonko level, plus their pets, artifacts, weapons, gears, summons, broken-ass World Items, etc.
The Great Kingdom never stood a chance.)
And so, the kingdom fell.
But the real problem started after that.
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The Fall of Supreme Beings
At first, things were great for these supreme beings. They had conquered a world! But then they realized....
They were literally unstoppable.
So instead of ruling responsibly, they did whatever they wanted.
Built harems. Messed around. Played hero vs. villain RPGs.
(Think about it—if you had the power to destroy the world, would you still work a 9 to 5 job? Probably not.)
Once in a while, they'd remember to look for Momonga, but… eh, having fun came first.
Meanwhile, the Five Elders and members of 20 Kingdom started to panic.
"We tricked them into taking over… but now they're stealing our throne! This was not the plan. This is not fun."
What really freaked them out? One of the supreme beings (a certain helpful, world champion level guy) had already wiped out an entire tyrannical royal bloodline.
"What if he gets bored and kills us next? We need a plan."
And so, the Five Elders came to a horrifying conclusion.
"If one of them ever decides they don't like us, we're screwed."
"We need to get rid of them before they get rid of us."
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The Great Divide:
The War Between the Supreme Beings
To counter this, the Five Elders manipulated the supreme beings into splitting into two factions.
One faction wanted total freedom and to do whatever they pleased.
The other believed in protecting humanity.
At first, the two sides just had minor conflicts.
But thanks to the Five Elders and others pushing the conflict further, war broke out.
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Supreme Beings Sealed:
At last, the war ended with them being sealed away.
(Because some Devil Fruits were truly broken, and of course, many had powers to seal anyone. But majorly infighting cause the great downfall of Supreme Beings.)
Over 800 years, some eventually died—as most of them weren't immortal.
They weren't human, and some long-lived races could only last so long.
The Fish-Men, once the descendants of a Supreme Being, were reduced to just another race of "fish."
At some point, their connection to their ancestor was completely forgotten.
Could they free him? Sure. But would they want to? Hell no.
(If he gets out, he might kill them all for abandoning him, as he might have gone insane.)
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Alabasta's Role in History:
Two Supreme Beings once lived in Alabasta.
One was a birdman, the other a dog-headed warrior.
The people of Alabasta were fiercely loyal to them, making Alabasta an important historical stronghold.
Roger, using his Voice of All Things, heard the thoughts of the sealed Supreme Beings.
He realized that after 800 years in isolation, they just wanted to destroy the world. So, he refused to free them.
The Five Elders, unaware of this, panicked, as they just saw a guy who knew too much and killed him.
Roger, in his final moments, saw their betrayal and thought.
"Oh? You guys wanna play it like that? Fine. Then I'll just burn your entire world down with my last move."
(The Five Elders put too much faith in memory-altering Devil Fruits and didn't realize Roger had planned their downfall.)
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World Government vs. Ainz Ooal Gown – Power Levels
The World Government (including the Holy Knights) today has around 20 Admiral-level fighters.
-> Without World Items, they can at least fight Ainz Ooal Gown.
-> But if Ainz uses World Items? He solos the entire World Government. (Because pay-to-win always wins.)
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Vegapunk: He is a descendant of the Supreme Being associated with Pluton. He inherited their genius intellect.
Combined with the Brain-Brain Fruit, he's basically unstoppable.