Paradise Island.
Onyankopon was the first to leave the construction sites. Even though he was the chief engineer overseeing the island's development, there was still a dream buried in his heart—one he had failed to complete back then. Because of that, he could never let go of the things he wanted to achieve, the design he still needed to finish.
Building railways on this island and planning other large-scale projects—sure, that was great work too.
But it wasn't what he truly wanted.
What he wanted was to complete the work of his entire life.
His plans and blueprints had once been stored in his home's basement, but that basement had already been destroyed.
He had gone abroad and returned to his original homeland to check on it, only to find it shattered beyond recognition—trampled by countless people, no longer anything like it had once been.
So Onyankopon returned to Paradise Island, determined to realize his dream here.
Because on this island, he found the only place that could truly keep him far from war.
Only here could he calmly complete his experiments without anyone disturbing him.
Still, the endless stream of construction work on the island made him feel intensely irritated.
Not because he didn't want to help the people inside the Walls—
But because he felt he didn't have time.
Projects came one after another, leaving him almost no chance to breathe.
And the island's leaders were smart. They knew he possessed technology the island didn't have, so they wanted him to pour out everything he knew and spend his entire life serving the island with tireless devotion.
That could have been a worthy lifelong career in its own right.
But Onyankopon didn't want that.
He didn't like being treated that way.
Since childhood, whenever someone tried to force him to do anything, he would feel annoyed and depressed.
One, because he hadn't had the power to resist.
Two, because he felt the world was too cruel—never giving him any free time to complete what belonged to him.
Fortunately, the island was growing stronger with each passing day. He no longer had to keep watching every project like a hawk, guarding against mistakes.
To ensure the island's construction wouldn't stall the moment he stepped away, he had trained many apprentices long ago—teaching them his skills so they could carry them forward.
He told them to spread it: one teaches ten, ten teach a hundred, until it ends up in textbooks—until everyone understands exactly how the world's "proud" machines were made.
And now, his plan truly had worked.
His apprentices were diligent, and when learning new knowledge they were ravenous—quickly mastering all of his techniques and experience.
It filled him with joy.
Because at last, he had time to complete the work he'd poured his heart into.
Once his apprentices fully took over his responsibilities, he retired and returned to his country.
But what he didn't expect… was that in his own country, he would be treated like less than human.
Those people were of the same race as him, yet they didn't accept him. They believed he had done countless wrongs for the world—helping that "devil's nation" become strong.
The president of Laibusi had him thrown into prison and intended to have him executed by slow slicing—dying under the cruelest punishment in the most unbearable pain.
Fortunately, Paradise Island—the place he had fought to build for so long—did not abandon him.
Eldia immediately issued a notice to Laibusi, demanding they release Onyankopon at once.
Under pressure from the Rumbling, they compromised and ultimately returned him.
From that day on, Onyankopon never once thought about going back to his country.
Toward his homeland, he no longer felt even a trace of longing.
Because he believed those people had gone mad—convinced he was the world's sinner.
So if they insisted on calling him a sinner…
Then he would simply become that sinner to the bitter end.
He would devote his strongest technology and all his effort to this country—bringing to life the product he believed he was meant to complete in his lifetime.
And so, he knocked on the door of the island's true king—Roger Eikam—and told him his idea.
Roger hadn't cared much about this man before. He didn't know what kind of skill Onyankopon truly possessed.
But after hearing the full concept, Roger's interest ignited immediately—
Because that thing was no ordinary invention.
According to Onyankopon, it had extraordinary capabilities.
It could allow a species that couldn't fly… to soar into the sky.
And it could allow a species that couldn't swim… to dive into the deep sea.
The more Roger thought about it, the more a single name felt appropriate—
the Mechanical Core.
Using mechanical power to elevate a species.
If it were anyone else, they might not be very interested, thinking it was nothing special.
But Roger found it rare and valuable.
First, he had always been fascinated by machinery. Back when the Survey Corps gave him the ODM gear, he'd been excited for a long time, marveling at humanity's hard work and ingenuity.
Now it seemed this brilliant craftsman before him truly was one of humanity's finest minds.
So Roger assigned him a laboratory dedicated to researching this device, and provided many assistants to support him.
With funding and backing secured, Onyankopon's experiments accelerated rapidly—his progress became astonishing.
He surged forward, outpacing the pace of his original research.
And soon, that thing was finally completed.
Onyankopon could already foresee it: this invention would bring massive transformation to society—economics and everything else.
Even if used in war, it would be a terrifying weapon.
This device had lived in his mind for years, but he had never been able to fully build it.
As for what consequences would follow once it existed…
He hadn't truly considered it.
He only believed that if he went through his entire life with nothing he could truly present to the world, then he didn't deserve to call himself a scientist or an engineer.
Now the Mechanical Core had been born.
And it had reached its complete form.
After repeated tests, it could eliminate disability for countless people—granting them prosthetic limbs at prices ordinary people could afford, allowing them to return to normal life.
In the time that followed, he shared his research成果 on the world forum—and it caused an uproar across the entire world.
Every nation scrambled to flatter him, wanting to poach him.
But what shocked them was that Onyankopon rejected them harshly—without hesitation. Even his mother country was turned down coldly.
"When I was at my most desperate and helpless, it was Eldia on Paradise Island that gave me hope to live again. I built many projects for their nation, and I completed many studies and experiments. This thing itself was only reborn because of them—it has nothing to do with me. If you want it, then go ask Roger for it."
He said it calmly, hiding his achievements and refusing credit.