Training Method That Treats Devil Fruits Like Dumbbells

A full week.

Mount Colubo practically turned into a living hell.

Cries of agony, the sounds of colliding flesh, and the roar of lightning splitting rock echoed in a symphony through the mountain forest every single day.

Under the dual torment of Lei En's near-demented lightning tempering and Bone Reforging, Monkey D. Luffy and Ace's strike resistance skyrocketed exponentially, as if riding a rocket.

As for them now, the moment they saw a faint trace of dark blue electrical current flickering on Lei En's fingertips, their entire bodies would convulse in conditioned reflex, acting as obediently as two declawed kittens.

Especially Ace, whose inherent extremism and arrogance were thoroughly crushed by Lei En using the simplest and most brutal physical methods.

Looking into Lei En's eyes, besides bottomless awe, not a single trace of rebellious intent could be found.

Whew... The warmup stage is barely passing.

Lei En sat atop a massive boulder, looking with satisfaction down at the two brats below who, despite panting heavily, possessed muscle lines noticeably sturdier than a week prior by a large margin.

"Next up, we enter the second stage—guidance of strength and Haki."

He pulled a special Seastone chain, thick as a child's arm and looted from Sky Island, out of his system space and tossed it casually onto the ground, producing a dull impact sound.

Clang!

Monkey D. Luffy and Ace looked at the pitch-black chain, an extremely ominous premonition instantly rising within their hearts.

"Boss, what... what is this thing?"

Monkey D. Luffy asked cautiously. He had already grown extremely accustomed to switching to calling him boss; calling him instructor tended to get one electrocuted.

Lei En did not answer directly.

He stood up, walked to the edge of the cliff, and looked at the roaring ocean below.

"Go."

Lei En pointed toward the sea surface, his tone unquestioning.

"You two, go catch two Nearshore Kings over fifty meters in length for me and bring them up."

"Huh?!"

Monkey D. Luffy and Ace exclaimed in unison.

"Fifty meters? Boss, you've got to be kidding me, right?" Ace swallowed a mouthful of saliva. Although he had grown much stronger by now, going bare-handed into the sea to catch such massive Sea Kings was just too absurd.

"Less chatter, go or I'm adding a ten-thousand-volts electrotherapy set."

A flash of electricity flickered on Lei En's fingertips, startling the two into a fit of shudders as they scrambled frantically toward the shore.

Half an hour later.

Accompanied by two massive roars, two Nearshore Kings, so enormous they resembled small mountains, were dragged and pulled ashore by Monkey D. Luffy and Ace using every ounce of their strength.

The two collapsed onto the beach in exhaustion, panting heavily with great gasps.

"Good."

Lei En had appeared behind them at some unknown point.

Using that thick Seastone chain, he tied the two frantically struggling Nearshore Kings together with extreme brutality.

Then, like kicking a football, he kicked the two ends of the chain toward the feet of Monkey D. Luffy and Ace respectively.

"Now, use this thing as a dumbbell and lift it up for me."

Lei En pointed at the two giant beasts whose combined weight reached tens of thousands of catties, speaking casually.

The air fell silent instantly.

Monkey D. Luffy and Ace looked at Lei En as if looking at a lunatic, their jaws nearly dropping to the ground.

"You... you've got to be kidding!"

Monkey D. Luffy grabbed his hair in a frenzy, protesting loudly.

"This thing weighs at least tens of thousands of catties! And this chain..."

He tentatively touched the pitch-black chain with his hand, and an extremely bizarre sense of powerlessness instantly swept through his entire body, causing his legs to go soft and sending him crashing directly to the ground.

"It's Seastone! I'm a Devil Fruit user! Touching this thing leaves me without even an ounce of strength, how could I possibly lift it!"

Monkey D. Luffy was on the verge of tears, feeling as though this was an utterly impossible task.

Ace, standing off to the side, was not a user, but looking at the mountain-sized sea beast, he also felt a wave of scalp-numbing dread.

"Impossible? In my dictionary, there is no such word as impossible."

Lei En sneered, instantly condensing a dark blue longwhip formed of pure high-pressure lightning in his hand.

Snap!

The lightning whip lashed through midair with a sharp, resounding crack, filling the air with a pungent odor of ozone.

"If you don't force yourselves, how are you going to break the side effects of Devil Fruits?"

Lei En gazed down at Monkey D. Luffy sprawled on the ground with an icy-cold expression.

"Fruit abilities are merely supplementary; true powerhouses rely on their own physiques and Haki pushing past limits!"

"A bit of Seastone turns you into a weakling? Then once you reach the New World and encounter those monsters proficient in Armament Haki and Seastone weapons, you can only wait to die!"

He slammed his hand forward, swinging the lightning whip without mercy to strike the beach beside Monkey D. Luffy and Ace, blasting out a scorched, blackened crater.

"Stop making excuses for yourselves! Wrap the chain around your bodies!"

"Weighted runs around Mount Colubo, ten laps! If you can't finish running, nobody eats today, and you'll all receive the million-volt baptism!"

Faced with Lei En's utterly demented coercion, Monkey D. Luffy and Ace no longer dared to utter a single word of defiance.

Gritting their teeth, they summoned every last shred of strength remaining in their bodies and tightly wound the heavy Seastone chains around their shoulders.

Ugh-ah—!

The moment they stood up, the terrifying weight pressed down on their legs until they trembled violently, their knees on the verge of shattering.

Especially for Monkey D. Luffy, the powerlessness emitted by the Seastone made him feel as though every ounce of strength had been drained from his body, making even breathing exceptionally difficult.

Yet he knew that if he stopped, what awaited him was electric shocks a hundred times more painful than this.

"I... I am the man... who's going to become the King of the Pirates!"

Monkey D. Luffy let out a roar of resentment, his eyes turning bloodshot.

Relying on the muscle memory forged by Lei En over the past week and an utterly stubborn, unyielding drive, he dragged the massive Sea King and took his first step with extreme difficulty.

"One step... two steps..."

Ace refused to be outdone either. His lone-wolf eyes burned with raging fire as he closely followed behind Monkey D. Luffy.

Two diminutive figures, shouldering sea beasts as heavy as mountains, began a tragic, arduous crawl across this rugged and steep Mount Colubo.

Every single step left a deep footprint in the ground.

Sweat pelted the soil like raindrops, mingling with the blood oozing from their scraped flesh.

Lei En sat on the edge of the cliff, munching on an apple while watching the two figures below crawling as slowly as snails yet never giving up.

His Observation Haki perceived it clearly.

Under this extreme physical squeeze and the oppression of Seastone, the massive potential originally dormant within Monkey D. Luffy and Ace was being desperately squeezed and activated at a speed akin to a volcanic eruption!

Especially Monkey D. Luffy; under the continuous weakening of the Seastone, his rubber cells unexpectedly began to generate an extremely bizarre resistant mutation in order to maintain muscle function.

The foundation of his basic body arts and strength was soaring wildly at a monstrous pace!

"At this rate..."

Lei En tossed away the apple core and clapped his hands with satisfaction.

"In half a month at most, I can officially teach them how to wield Armament Haki."

Just at that moment, Lei En's sharp hearing suddenly captured an extremely faint, unusual sound echoing from deep within the mountain forest.

Rustle...

It sounded as though someone was approaching with extreme caution.

Furthermore, their presence was concealed exceptionally well; had Lei En's Observation Haki not been extraordinarily monstrous, he likely would not have discovered them.

"Oh? Another rat has crept up?"

The corners of Lei En's mouth curled into an amused sneer. He did not turn around, merely leaning lazily against the stone.

"Since you're here, stop hiding in the shadows."

His voice was not loud, yet it clearly penetrated the woods.

"Let me guess: are you here to collect the bodies of these two brats, or... to pick a fight with me?"