The Shikon Jewel possesses time-manipulation abilities, and when stimulated by the Time-Time Fruit, these abilities were finally manifested.
It felt like swimming through the earth; Yuan Yi expended considerable energy to enter the range of its gravitational pull.
Then...
He returned to his world!
As mentioned, he merely set the stage in that world, preparing for events that would unfold over the next ten to twenty years.
But in the process, a year had passed.
If his true self had been in this world, bringing back his avatars would take a year. But since his true self was in the future, he could return earlier, albeit after a year had elapsed.
During his absence, the world continued to develop, so emotional values did not disappear, but they would weaken slightly over a year before returning to his body.
Now, it was 1495 in the Sea Calendar. Usually, this would be the year Roger and Shiki would have their excellent sea battle at Ed War.
But in this world, Shiki had already fallen, and Roger was too powerful compared to others except Yuan Yi, making it unlikely for such a great sea battle to occur.
First, he placed Gremmy's brain on Pandora Island, instructing Vegapunk to create a suitable human vessel based on the brain.
Of course, Vegapunk could not be aware of this, so it had to be done under control.
All materials used had to be the best.
Shortly after, a new visitor arrived on Pandora Island.
Garp!
For many years, Garp had continued his naval duties with only one arm. It wasn't that the World Government had forgotten about him; they had been researching mechanical arms all this time.
But mechanical arms couldn't conduct Haki well. Though they could incorporate Seastone, that would only target specific threats.
A mechanical arm would be a waste for someone as skilled as Garp.
In recent years, one of Vegapunk's research projects was the biological arm transplant.
Recently, Vegapunk successfully developed mature technology.
"It's been so long, I almost got used to it."
Garp stepped off the ship, flexing his remaining arm.
"Well, one arm looks too pitiful."
Waiting for him was Sengoku. Knowing his old friend was coming, Sengoku naturally came to greet him.
The Marine Headquarters was separated from Pandora Island by the Red Line, but the Black Order was nearby, so Sengoku often visited.
He liked to check on the children's training with Pandora's Box. They were primarily orphans found by the World Government, who had no home but now had food and protection from pirates, though they had to face the trials of demons.
Initially, it was dangerous, but then Vegapunk mass-produced super soldier serum, which, when injected, made people's minds more resilient, providing some resistance to demonic temptations.
So things improved significantly.
Every year, a batch of children with superpowers from Pandora's Box training were sent to various government departments, destined to become the backbone in a decade.
"I wonder what kind of arm Punk has prepared for me," Garp said, smiling at Sengoku as he stepped off.
They hadn't seen each other in a while. One was a Marine Vice-Admiral, the other a General in the Black Order. Both were high-ranking but in different departments, busy with their own duties, rarely visiting each other's headquarters.
Sengoku led Garp into the depths of Pandora Island. "An arm... of a demon."
Sengoku had inquired with Vegapunk before arriving and knew a bit. He whispered, "It's akin to Ann's 'Shadow Cutter'."
Shadow Cutter has gained great fame in the world recently. Though not a supreme blade, it was a coveted weapon.
With Shadow Cutter, Ann could chase the Roger Pirates globally without arousing suspicion.
"Punk explained it to me, but for details, you'll have to hear it from him."
Sengoku only knew a little, as Vegapunk had kept many secrets, seemingly wanting a grand reveal of his invention.
"Making such a fuss." Garp scratched his head, curious about his new arm.
Ann had made such a name for herself with a sword, and now he was getting a similar arm?
"Hurry up!"
Garp's excitement drove him forward, soon overtaking Sengoku, who initially led the way.
"Really..." Sengoku sighed, then shouted, "Don't get lost running ahead!"
Soon, they reached Vega punk's lab.
Vegapunk had seen them arriving on the monitors and greeted them at the experiment table.
"You're quick. I was eager to see the results of my new invention."
Vegapunk pointed to an arm on the table. "Come, Marine Hero Garp, try my strongest right arm!"
"Strongest right arm, how strong?"
Garp approached, noticing it wasn't mechanical but similar to an average arm tailored to his size.
It matched his remaining left arm.
"To transplant body parts, only Zoan-type Devil Fruits work, as they have a stronger consciousness to integrate with the body."
Vegapunk excitedly circled the table, explaining, "After fully activating the arm with Zoan Devil Fruit and demon cells, it will bind with your flesh. But you must be aware..."
"Like how Ann conquered her Shadow Cutter, you must constantly battle your right arm. Its consciousness from the Zoan fruit is strong and will try to take over before you awaken."
Vegapunk stopped before Garp, solemnly asking, "Even so, do you choose this arm transplant? I have safer options, too."