In the year 1490 of the Sea Circle Calendar, many significant events occurred across the world. The most shocking of all was the murder of Navy Admiral "Black Arm" Zephyr's (age 42) family by pirates, which led him to develop a deep hatred for pirates. He began semi-retiring from the Navy but retained his admiral rank, later transitioning to become an instructor at the Navy training camp.
That same year, Magma Fruit user "Red Dog" Sakazuki and Glint Fruit user "Yellow Monkey" Borsalino joined the Navy. Due to their exceptional strength and immense potential, they were admitted into the Navy training camp.
Also in that year, on April 1st, on a deserted island in the New World of the second half of the Grand Line...
A three-masted sailing ship was anchored beside the island. On its deck stood two figures: one was a youthful boy with white hair, brown skin, black wings, and a somewhat immature face; the other was a slightly plump young man with a bald head, sunglasses, purple lips, and a golden braid on his head. They gazed toward the depths of the island, where tremors occasionally rumbled.
"Hey King, what's gotten into Boss Kaidou lately? This is the third small island we've encountered in half a month, and each time Boss Kaidou goes on a rampage for hours," the not-yet-fully-grown Queen remarked, puffing on a cigar as he spoke to King beside him.
"We just need to obediently follow Boss Kaidou's orders and wait here for him to return. If you're really that bored, you should train hard as Boss Kaidou said and improve your strength," King replied expressionlessly.
Even though they had become comrades, King still held no fondness for this man who had been studying him not long ago.
After speaking, King directly flapped his wings and soared into the sky.
"Hmph! Just a test subject. If Boss Kaidou hadn't taken a liking to you, I'd still be studying you," Queen grumbled discontentedly as he watched King leave, then involuntarily glanced toward the island where tremors continued to occasionally shake the ground.
······
Meanwhile, deep in the heart of the island...
"Urorororororo..."
Accompanied by massive tremors and roaring echoes across the entire island.
"Boom... Boom... Boom..."
A massive cyan dragon, over a kilometer long and dozens of meters wide, moved with unstoppable momentum through the island. Everything in its path was destroyed—thick giant trees, solid mountain rocks—nothing could hinder its advance in the slightest.
After a long while, as if having vented enough, the enormous figure gradually came to a stop. Then it raised its massive dragon head high, terrifying vertical pupils like lanterns concealing boundless excitement as it gazed toward the dark ocean in the distance. It opened its abyss-like maw, where intense flames gathered.
"Heat Breath!"
"BOOM——!"
A several-kilometer-long Heat Breath shot across the sea, illuminating the entire world while causing the ocean to boil and bubble intensely.
One minute later, the flames finally extinguished. The gigantic body began to gradually shrink, transforming into a man who stood like a giant—seven meters tall with a burly build, bulging muscles, and wielding a black spiked club.
As the kanabo in his hand swung through the air, terrifying techniques intertwined with black-and-red lightning emerged one after another, each strike causing the entire island to tremble as if shaken by earthquakes.
"Thunder Bagua!!!"
"Conqueror of the Three Worlds·Pull!"
"Adamantine·Arrow!"
"Drunken Thunder Wheel·Into Hell!"
"Kundali·Dragon Flourishing Army!"
"Roaring Thunder·Bagua!"
"Yamāntaka·Thunder Bagua!"
...
Had he not restrained much of his physical strength and Haki, the entire island would have already been destroyed. Even so, the terrifying power resembling a cataclysmic disaster made the island experience what felt like hurricane-force winds and torrential rains exceeding category ten.
After nearly three hours of such outpouring, everything finally ceased. The massive, burly figure plopped down onto the devastated land, grabbing a giant gourd of sake nearby and gulping it down noisily.
Simultaneously, joyous laughter erupted once more.
"Urorororororo... Truly magnificent! Worthy of being one of the future Four Emperors of the New World, the body of Kaidou, hailed as the King of Beasts and the World's Strongest Creature. Whether it's this virtually indestructible physique, the power of the top-tier Mythical Zoan Fish-Fruit Azure Dragon Form, or the God-level Haki—all are unbelievably powerful!"
Kaidou laughed heartily as he surveyed the island ravaged by his outburst.
Who could have imagined that an ordinary office worker from Earth, living a life of drudgery day after day, would wake up one day transformed into Kaidou, one of the characters from "One Piece"—a manga he had given up following. As one of the "Big Three" shonen manga, "One Piece" had once been among his favorite series to keep up with.
However, after the plot entered the Wano Country arc, with its increasingly twisted characters and endless fake-out deaths, this man's passion for "One Piece" began to wane. His fondness for the main cast diminished, replaced by a growing sympathy for Kaidou, the major antagonist of this arc—affectionately dubbed "Teacher Kaidou" by fans. Still, he understood that villains being defeated by the protagonist was inevitable, so he held no strong feelings about the final outcome.
Later, when the storyline involving the "Hard Work King" Koby emerged, it became the final straw that made the then-ordinary man drop the series entirely. Only through occasional short videos did he gain a rough understanding of the subsequent plot developments.
But none of that mattered now. Those events were decades away. With his transmigration as Kaidou, the world's storyline had already begun diverging from the original.
For instance, King—who should have consumed the Zoan·Dragon-Dragon Fruit·Ancient Species·Pteranodon Model—and Queen—who should have eaten the Zoan·Dragon-Dragon Fruit·Ancient Species·Brachiosaurus Model—both refrained from consuming these Devil Fruits stolen from the laboratory due to his intervention.
Moreover, since crossing over, perhaps because his soul from another world was adapting, Kaidou felt his body growing stronger—not just marginally, but comprehensively and continuously. The density of his bones, the toughness of his flesh, his reaction speed, his recovery rate—all had significantly improved.
Not only his physical body, but Kaidou felt that all three types of Haki within him had grown stronger by more than one level. His Observation Haki could now barely glimpse into the future, though it worked intermittently. Both the quality and quantity of his Armament Haki had significantly improved. And when fully unleashed, his Conqueror's Haki could now exert a certain influence on reality.
Kaidou sensed that his current strength might not be inferior to his future self during the Wano Country arc. Of course, this was merely Kaidou's vague intuition. Although he now possessed all of Kaidou's memories and combat experience, making him far from weak, he still fell short compared to his future self—primarily due to lacking battle experience against Yonko-level powerhouses.