Leon frowned, but his eyes showed no trace of fear as he stared down the monstrous Kaido.
The ten-year-old scientist hadn't expected the Emperor to show up here of all places and certainly not this fast.
'This definitely complicated things.'
"BOOM!"
A deafening crash echoed behind Leon.
"Dr. Leon," he rumbled, his voice dripping with arrogance.
"I hope you're not going to be an idiot about this. You really don't want to see me angry."
The King of the Beasts' voice echoed in the ruined lab.
His eyes burned with a mixture of greed and pure, animalistic madness.
Leon looked up at the giant before him, his expression eerily calm.
He could read the situation perfectly.
Kaido had no intention of letting him live if he refused.
The moment Leon said no, that iron club would come crashing down on his head without a second's hesitation.
"Well, Dr. Leon? Have you thought it over? I've given you plenty of time," Kaido sneered, his gaze locked on the small child.
After a moment of silence, Leon simply shook his head.
Seeing the boy reject him so plainly, a cold fury glinted in Kaido's eyes.
He wasn't used to being told no.
Usually, anyone who dared to refuse his offer was already dead.
"Are you sure about that?" Kaido's voice dropped, becoming dangerously low.
He was willing to give the kid one last chance.
A genius like this was too valuable to just kill.
"I've made my position clear," Leon stated, his voice steady as he watched Kaido's face twist with rage.
"I work for the Marines. You represent the opposite of that. I'm not interested."
"Remember, kid, you asked for this!" Kaido roared, his patience finally gone.
"If you won't be of use to me, then you're better off dead!"
He bellowed, swinging his massive iron club down.
The weapon was wreathed in black and red flames, and a wave of suffocating heat washed over Leon.
As the club descended, an inferno of black flames erupted from it, ready to vaporize anything it touched.
Leon knew that if that attack landed, there would be nothing left of him.
But he was the world's greatest scientist.
Of course he had an ace up his sleeve.
Just as Kaido's club was about to crush him, a sleek figure appeared in a blur above Leon.
CLANG!
With a deafening shriek of metal on metal, the unstoppable club was brought to a dead halt.
Kaido grunted in disbelief and slammed his club down again with even more force.
The figure didn't budge an inch.
"What is this...?" Kaido bellowed. "Who the hell are you?!"
As the smoke cleared, a figure with dark skin, white hair, and massive black wings stood protectively in front of Leon. Its voice was calm and synthetic.
"Unit PX-000. My primary directive is to ensure the safety of my creator. Please stand back, Doctor Leon."
Leon casually patted the dust from his clothes and began gathering some of his scattered research notes, completely unfazed by the chaos.
Kaido, however, was stunned.
His eyes locked onto the figure protecting the boy.
"Impossible... That's a Seraphim, but it's not like the others."
His eyes narrowed.
With a deafening roar, he swung his massive iron club, wrapping it in a vortex of lightning, fire, and howling wind.
The next instant, he lunged forward like a demonic dragon, closing the distance in a heartbeat.
He brought the super-charged weapon down directly on the Seraphim standing in his way.
His face was a mask of pure murderous rage.
"Don't think some fancy toy can scare me, boy! I am an Emperor of the Sea!"
With a final, earth-shattering roar, the club fell with enough force to twist the very air around it.
In response, the special Seraphim simply raised its head, watching the attack descend.
CLANG!
The Seraphim lifted its right arm and effortlessly blocked Kaido's ferocious killing blow.
The attack, powerful enough to level a mountain, didn't even scratch its skin.
Seeing his ultimate move stopped so easily, Kaido's jaw went slack with shock.
'What the hell is this thing? Where did it come from?!' he thought, his mind reeling.
Seeing the Seraphim completely casual stance made his blood boil.
The Seraphim turned its head slightly, its calm gaze falling upon its creator.
"Please issue your orders, Dr. Leon."
Leon looked past his creation at the fuming Emperor and said calmly, "Engage. Drive him out of Mariejois."
The moment the order was given, the Seraphim—who looked tiny compared to Kaido—moved.
It pressed its palm flat against Kaido's massive abdomen.
An unbelievably bright laser erupted from its hand.
BOOM!
The immense, crushing pressure that Kaido always radiated vanished in an instant.
His huge body was blasted backward by the terrifying force, flying clean over the edge of the Holy Land's plateau.
A gaping, glowing hole was seared straight through his torso.
"Damn it... how could it be this strong...?" Kaido muttered, clutching his wound as he struggled to his feet in the massive crater he'd created.
"Target has not yet vacated the designated territory. Continuing mission."
The Seraphim voice was cold and emotionless.
It appeared before Kaido in a flash.
The anger in the Emperor's eyes burned hotter than ever.
"You little tin can, you think you've won?!"
Kaido roared, swinging his club with all his might once again.
CLANG!
The same crisp sound echoed as the Seraphim blocked the menacing blow with a single arm.
"PX-000 mission protocols active," it said to itself.
Then, raising its hand again, it unleashed a continuous barrage of laser beams that hammered into Kaido's famously indestructible body.
Explosion after explosion sent the mighty Emperor stumbling backward, again and again.
The power of this single Seraphim was beyond anything Kaido could have imagined.
This machine didn't have any Devil Fruit powers, just absurd physical strength and a laser far more potent than Kizaru's.
The combination was a nightmare.
Kaido, now seriously injured, spat out a mouthful of blood.
He knew that if he kept fighting this inexhaustible monster, he would be the one to fall.
He was brave, but he wasn't stupid.
In just ten minutes of fighting, he hadn't landed a single clean hit.
He was being completely and utterly hammered, unable to so much as scratch his opponent's defense, while its lasers were making his whole body go numb.
"I'll smash you to pieces!" he howled in helpless fury.
With a final growl, he launched himself out of Mariejois's urban area.
The moment his feet left the boundary, the Seraphim that had been relentlessly attacking him simply vanished from sight.
Seeing the monster was finally gone, Kaido let out a shaky breath of relief.
At this point, he would rather fight all three Marine Admirals at once than face that thing alone again.
"That thing's power is just... wrong," Kaido muttered, his pride in tatters.
He transformed into his full dragon form and soared into the sky.
He knew he had to get back to his allies and the scientists they were working with.
Only by advancing his own technology did he stand a chance of coming back from this.
....
Back in the heart of the Holy Land, the Five Elders circled the Seraphim, looking at it with the wonder of children.
This was Leon's hidden trump card, a masterpiece far beyond their standard models.
"Kaido's full-power attack didn't even leave a mark. A defensive ability like that... it's terrifying!" one of the Elders exclaimed in awe.
Leon, however, wasn't celebrating.
He was busy scribbling in a small notebook, recording streams of data.
Although the Seraphim first combat trial was, by all accounts, "perfect," Leon saw room for improvement.
The battle had revealed minor inefficiencies, flaws that he could correct with more calculations and updated modules.
As he jotted down his plans, Leon finally looked up at the astonished Elders and said.
"There's a reason this Seraphim is so powerful."
He tapped his pen on his notes.
"The core materials used to build it aren't from this world. Its entire skeletal structure is made from a strange metal called 'Adamantium.' It's what makes it virtually indestructible."