For many years, Kahn has been eyeing the knowledge stored in Dr. Vegapunk's brain.
To be precise, he is focused on the Seraphim, artificial Devil Fruits, and the knowledge of replicating Devil Fruit powers.
However, Kahn has not unlocked any of this knowledge. Even after all these years, despite absorbing the expertise of Queen, Vinsmoke Judge, and even Caesar, Kahn has become an outstanding scientist, but he still hasn't been able to develop the Lineage Factor to Vegapunk's level.
Ever since Kahn became a scientist, he has been patiently waiting for Vegapunk to unlock the secrets of the Lineage Factor and Devil Fruits.
For this reason, Kahn also hides the existence of the "Cross Family" and forbids Viola, who ate the Paramecia Glare-Glare Fruit, and Carina, who consumed the Paramecia Whisper-Whisper Fruit and the Logia Dark-Dark Fruit, from revealing their abilities to the outside world.
Not only that, Kahn even made specialized combat uniforms for women like Boa Hancock and the Perfect Five, instructing them to use invisibility during missions and to leave no traces.
All of this preparation was for this very day!
After successfully turning Vegapunk into a doll using the power of the Op-Op Fruit to dismember him into dozens of pieces without giving him a chance to escape, and after eliminating his six clones, Kahn ordered Kuina to use the Float-Float Fruit to take control of Warhead Island.
Kahn then had Monet use the transfer ability of the Op-Op Fruit to teleport Sentomaru, who was in charge of protecting and monitoring Vegapunk, along with some Marines and CP agents, to the lab.
Just as they had done with Vegapunk and his clones, Granose and Monet acted swiftly, using the abilities of the Whisper-Whisper Fruit and the Op-Op Fruit to turn their enemies into dolls and dismember them into pieces.
After dealing with them, Granose skillfully used the conceptual power of the Whisper-Whisper Fruit to erase the "existence" of these individuals from the memories of all who knew or remembered them.
At this moment, the entire world has forgotten about Vegapunk, the world's greatest scientist whose wisdom was 500 years ahead of humanity.
Unless someone had prepared a Vegapunk file in advance or possessed a memory that could counter the conceptual power of the Whisper-Whisper Fruit, even with powerful Haki, it would be impossible to recall Vegapunk.
Unless Vegapunk had an immensely powerful Haki, strong enough to break free from the control of the Whisper-Whisper Fruit's rule over dolls and revert back into a human, the world would never remember him again.
Unfortunately, Vegapunk didn't possess such an ability and never got that chance.
After eliminating everyone, including Vegapunk, Kahn and his crew remained hidden in stealth mode, Kuina then used the Float-Float Fruit to lift Warhead Island and carry it to the White Sea, 7,000 meters above the ground.
For Kuina, now 24 years old and enhanced with genetic modification technology years ago, her physical strength is at the level of a highly advanced human, standing out even among them.
While Kuina, in her invisible state, lifted the entire Warhead Island, Kahn had the Perfect Five use the Teleportation Fruit to return them to the uninhabited island where Viola was waiting.
Finally, Kahn instructed Granose to temporarily remove Vegapunk's doll status and asked Monet to reattach Vegapunk's head. Using Observation Haki, Kahn then began reading Vegapunk's memories every day.
Just after reading the memory, Kahn's face, hidden under his invisible helmet, shifted in surprise.
The knowledge and memories stored in Vegapunk's brain were incredibly vast.
Even though he had distributed much of his knowledge across his six satellites, the remaining core memories and information in his main brain were still enough to make Kahn feel as if his Haki reserves were being drained, like a dam letting loose a flood.
Fortunately, over the years, Kahn's strength hadn't stagnated. He had reached a mysterious level of power.
Even though reading the mind of Vegapunk, a Paramecia Brain-Brain Fruit user, consumed a tremendous amount of Haki every second, Kahn's Haki reserves held up long enough for him to extract the information he wanted.
Once he finished reading what he needed, Kahn ordered Sugar to turn Vegapunk back into a doll and then had him dismembered again.
After having the Perfect Five teleport them to Slug Island, Kahn went to a specific location in the lab and pressed a sequence of buttons.
Instantly, all the monitoring devices hidden in countless corners of Warhead Island—which had been recording and transmitting data to the World Government via Den Den Mushi—shut down and entered sleep mode.
Next, Kahn accessed the database and deleted all the footage showing the island's shaking and the disappearance of Sentomaru and the others that had just been captured.
With all this done, Kahn and his crew finally lifted their stealth mode.
Now, even if the World Government reads through Vegapunk's archives or finds a way to counter the memory-erasing power of the Whisper-Whisper Fruit, they won't be able to recall Vegapunk, Slug Island or even locate an Eternal Pose leading to Slug Island. Neither Vegapunk nor Slug Island can be found anymore.
From Vegapunk's memory, Kahn had uncovered a critical piece of information.
Vegapunk never fully trusted the World Government. He had only joined them due to a lack of research funding.
In fact, most of the groundbreaking technologies Vegapunk had developed, from the Pacifista to laser tech, Seraphim, artificial Devil Fruits, and Devil Fruit replicas, had already been completed—except for space-jumping technology, which was still in progress.
He knew that when the World Government no longer found him valuable or believed they had enough of his inventions to maintain the world's balance for the next 800 years, his life would be in danger.
Thus, Vegapunk secretly modified Warhead Island.
While others could easily craft an Eternal Pose to track an island by simply digging up some soil—just like making a Vivre Card—this wasn't the case for Warhead Island. Even Raftel, the final island, was no exception to this method.
But Vegapunk had already solved that problem.
He not only transformed Warhead Island into a futuristic city but also secretly installed a device that could block its magnetic field.
When activated, this device would cause the Eternal Poses pointing to Warhead Island to spin erratically, malfunctioning just like a compass does in the Grand Line.
Clearly, Vegapunk had been preparing for a long time to break free from the control of the World Government—and he had multiple backup plans in place.
Thanks to Vegapunk's preparation, Kahn not only secured the island of the future but also didn't need to relocate any of the cities or machines on Warhead Island.
After activating the magnetic field shielding device, Kahn didn't return Warhead Island to the waters near Wano. Instead, he took it 10,000 meters into the sky, further lowering any suspicion of his involvement.
This was the same reason Kahn had ordered Carina and the others to retrieve the body of Shiki, the Golden Lion, and stage a mysterious disappearance.
Apart from wanting to obtain the Golden Lion's Lineage Factor, Kahn also planned to shift the blame onto the already dead Shiki.
Without Kahn's telekinetic power holding up the island, his involvement would be virtually undetectable.
This entire operation would be the perfect crime.
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