As the morning sun climbed above the mist-covered canopy of God Valley, a peculiar figure wandered the dense forest—a child, no older than ten, with feline ears twitching atop his head and a long, swaying tail behind him. At first glance, one might mistake him for the user of an ordinary Zoan-type Devil Fruit that granted the traits of a common cat. But that assumption would be dead wrong.
Unseen by ordinary eyes, a spectral marionette floated just above the boy's head—arms stretched wide, threads descending into his body like a puppeteer commanding a living doll. Every movement, every twitch of the boy's limbs, was not his own, but directed by the ghostly figure above. This strange and eerie scene was none other than Trafalgar D. Mundo, practicing his control over one of the most unusual and terrifying Devil Fruits in existence.
"It's been several days since I arrived here... and I can't lie, I've been enjoying it," Mundo thought to himself, his golden feline eyes half-lidded with contentment. "If not for the ticking time bomb set to go off after four years, I might even let myself celebrate."
In another life, Mundo was just an ordinary human—an aspiring surgeon cramming for his board exams, kept awake by three nights of Red Bull and adrenaline. But his body had limits his will did not. His heart gave out before his dreams did. When he awoke, he was no longer in his world… but in the brutal and chaotic sea of the One Piece world.
He had not come empty-handed.
Bestowed upon him were the memories and intellect of Dr. Genus, the mad genius from One Punch Man, a man so brilliant he had discovered the secret to de-aging and biological evolution. With that genius now fused into Mundo's mind, decades of research could be compressed into days, and his knowledge of biology, anatomy, and evolution far exceeded any scientist or doctor this world had ever seen.
And then there was the fruit.
The Neko-Neko no Mi, Model: Neferpitou. A Mythical Zoan of terrifying potential. It didn't just grant Mundo immense physical strength and cat-like agility—it gave him abilities that blurred the line between healer and killer. He could control puppets and corpses with spectral threads, stitch flesh without tools, and tear apart anatomy without leaving a wound. But that wasn't all—his fruit had evolved. By some divine or cursed design, it had absorbed elements of Kisuke Urahara's Bankai, particularly Benihime's surgical disassembly and reconfiguration powers. A true surgeon's Devil Fruit—one that could rival, even surpass, the legendary Ope Ope no Mi.
Right now, Mundo was training the fruit's puppeteer ability—starting with the simplest subject: himself.
"I'll stay in this form a while longer," he mused. "If I align my will with the fruit's instincts, maybe I can achieve Awakening sooner."
Ending his internal monologue, Mundo deactivated the puppeteer, letting his body relax. Then, folding himself into a near-impossible meditative pose—one that only a being with an impossibly flexible, enhanced body could perform—he sat in stillness. His breathing slowed. His aura dulled. For two hours, he remained in this perfect stillness.
But in that silence, something stirred.
The deeper he connected with the Neferpitou within, the more he felt its influence—a primal edge creeping into his thoughts. Not madness, but hunger. Bloodlust. The feline predator within him wanted more than control.
It wanted prey.
Sensing this shift, Mundo calmly broke his meditation. There was still time before he let that side loose. For now, he would continue learning—sharpening the blade of both science and instinct.
And when the world came looking for monsters… it would find him ready.
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Several more days passed on the wild and unpredictable island of God Valley, and Trafalgar D. Mundo's experiments had entered a new phase. The feline hybrid, once content to explore his Devil Fruit's puppeteering aspects, was now standing in a crude clearing deep within the forest, flanked by three of the most ferocious beasts the island had to offer.
A bear, a tiger, and a wolf—each subdued not through brute strength, but through careful dissection of their nervous systems and puppeteering mastery. Their eyes were dulled but still alive, bodies twitching as invisible threads danced from Mundo's fingers.
"It's time," he muttered under his breath.
Mundo had already achieved full self-control through his Marionette Dissection technique. Now, he was attempting something far more ambitious: the creation of a living chimera, a loyal beast crafted from the finest parts of nature and held together by his Devil Fruit's grotesque precision, fueled by the vision passed down through Dr. Genus's memories. The House of Evolution would have been proud.
The bear was chosen as the base for good reason. Its immense muscle density and unmatched durability made it the perfect foundation—a tank-like body capable of absorbing damage and dishing out raw power.
Then came the tiger. Mundo carefully severed the musculature around its limbs, extracting tendons and muscle fibers that were unnaturally springy, perfect for high-speed movement and reflexive twitching. Tigers had an exceptional neuromuscular connection, allowing for explosive bursts of motion, even in midair. That trait would be surgically wired into the bear's body.
Lastly, the wolf's head—not just for its appearance, but for its advanced jaw structure and instinct-driven brain. Mundo widened the skull and reinforced the jawline with hardened sinew and bone plating, extending its canines and sharpening the molars into shearing tools. The wolf's heightened senses and predator's intuition would give the creature a cunning edge no ordinary beast could match.
But Mundo didn't stop at anatomical stitching.
Using the Chimera Override ability from his fruit—an evolution of Neferpitou's grotesque puppetry and Benihime's reconfiguration—Mundo manually synchronized the nerve clusters and rerouted muscle memory, essentially teaching the body how to move as one unified being. Bones were fused, tendons re-threaded, arteries mapped, and redirected with spectral threads.
This was no corpse. This was no puppet.
This… was life reconstructed.
Mundo stood back, his breath steady, but his aura rippling with satisfaction and curiosity. The chimera beast shuddered, snarled, then rose to its feet with surprising fluidity. Its movements were uneven at first, like a newborn deer, but within moments, it adjusted. Instincts from each animal fired in perfect harmony. The beast circled Mundo once, sniffed the air—and then bowed its head.
Loyalty, as programmed.
"I'll name you… Kurodan."
And so, Kurodan—Mundo's first successful synthetic beast—was born. A creature forged from nature, science, and supernatural will.
Kurodan, who was given a name, showed its affection towards Mundo, as he recognize Mundo as it's creator, while Mundo gave back the affection that Kurodan was providing him.
"Can you hunt our food?" Mundo asked with calm authority.
The massive chimera, Kurodan, let out a guttural snort and nodded. In the next instant, it bolted into the forest, moving with a level of speed and agility that defied logic for something of its size and build. Its tiger-crafted limbs and wolf reflexes carried it between the trees like a silent storm. Mundo watched with narrowed eyes and a satisfied smirk.
"Good," he whispered. "Better than expected."
With Kurodan gone, Mundo turned inward, focusing not on external manipulation, but on internal evolution.
Without needing to shift into his Zoan hybrid or beast form, he activated his Devil Fruit's core ability. His fingers twitched, and the faint glimmer of spectral threads shimmered around his skin, though now, they turned inward, stitching and rewriting his own biology. He was no longer just enhancing; he was rewriting the blueprint of his base form.
Mundo began by targeting his muscle tissue. Using what he had learned from the tiger's anatomy, he began compressing the fibers of his muscles—not just bunching them, but refining them, stacking layer upon layer of tightly packed, high-efficiency strands.
The result was a miracle of unnatural biology: muscles that were more compact, more explosive, and far stronger than those of even the strongest natural beast. It was like coiling ten tons of force into the size of a child's arm. The same structure that let a tiger drag prey several times its weight was now scaled, amplified, and fused with human efficiency and control.
Sweat formed on Mundo's brow, but he didn't stop. He reinforced his joints, hardened his tendons, adjusted his nervous response speed—all using micro-scale puppeteering within his body. No machines. No drugs. Just willpower, knowledge, and a Mythical Zoan fruit.
When he finally stood tall again, his body looked nearly unchanged—no bulky frame, no monstrous transformation—but beneath the surface was a human forged into a living weapon.
He tested it.
Without even bracing, Mundo crouched slightly and leapt into the air.
FWOOM.
He soared higher than he ever had before—even in hybrid form. The trees became specks beneath him. The clouds were briefly within reach. For a moment, the sky felt like home.
"I wasn't even trying," he muttered in disbelief, grinning as the wind howled past him on the way down.
As he descended, he flipped lazily in the air, arms spread as if embracing gravity itself. His feet landed on the forest floor with a light thud, cracking the ground beneath from the force, yet leaving him unharmed.
Mundo exhaled slowly, eyes gleaming with ambition.
"I can't wait until I get my hands on the genetic code of those with real special traits…" he whispered, a spark of obsession lighting behind his calm facade.
The foundation was laid.
And the world had no idea what was coming.