A whole week passed.
Mount Colubo seemed to have turned into a living hell.
Screams, the sounds of bodies colliding, and the thunderous roar of lightning shattering rocks echoed through the mountains on schedule every day.
Under Lei En's nearly insane double torment of "Lightning Tempering" and "Bone Reforging," Monkey D. Luffy and Ace's ability to take a beating skyrocketed exponentially, as though they had boarded a rocket.
Now, whenever they saw even the faintest flicker of deep-blue electricity at Lei En's fingertips, their entire bodies would shudder on reflex. They were obedient as two kittens with their teeth pulled.
Ace in particular had had the stubbornness and pride carved into his bones completely crushed by Lei En's simplest and most brutal physical methods.
When he looked at Lei En now, there was nothing in his eyes but bottomless awe. Not a trace of resistance remained.
"Phew... The warm-up phase barely passes."
Lei En sat atop a massive boulder, looking down with satisfaction at the two brats below. Though they were panting heavily, their muscles had visibly become far more solid than they had been a week ago.
"Next, we enter phase two—guiding strength and Haki."
He pulled out a specially made Seastone chain, as thick as a child's arm, which he had looted from Sky Island, and casually tossed it onto the ground with a heavy thud.
Clang!
The instant Monkey D. Luffy and Ace saw the pitch-black chain, an intensely ominous feeling rose in their hearts.
"Boss, wh... what is that?"
Monkey D. Luffy asked carefully. He had already become very skilled at calling Lei En "Boss." Calling him instructor made it too easy to get shocked.
Lei En did not answer him directly.
He stood and walked to the edge of the cliff, gazing down at the turbulent sea below.
"Go."
Lei En pointed at the ocean, his tone leaving no room for argument.
"You two, catch me two Nearshore Kings over fifty meters long."
"Huh?!"
Monkey D. Luffy and Ace cried out at the same time.
"Fifty meters? Boss, you're joking, right?" Ace swallowed hard. Though he had grown much stronger, going into the sea barehanded to catch Sea Kings that huge was utterly ridiculous.
"Stop whining. Refuse, and I'll add a Ten Thousand Volts: Electrotherapy package."
A flicker of electricity flashed from Lei En's fingertips. The two of them jolted in fright and scrambled toward the shore.
Half an hour later.
Accompanied by two tremendous booms, Monkey D. Luffy and Ace dragged two Nearshore Kings as enormous as small mountains onto the beach with every ounce of strength they had.
The two collapsed onto the sand, gasping for air.
"Very good."
Lei En had somehow appeared behind them.
Using the thick Seastone chain, he brutally bound the two Nearshore Kings, which were still struggling desperately in their death throes.
Then, as if kicking a ball, he sent each end of the chain flying to Monkey D. Luffy and Ace's feet.
"Now, treat these things like dumbbells and lift them."
Lei En pointed at the two giant beasts, which together weighed tens of thousands of pounds, and spoke as if it were nothing.
The air fell silent in an instant.
Monkey D. Luffy and Ace stared at Lei En as though he were insane, their jaws nearly hitting the ground.
"Y-you've got to be kidding!"
Monkey D. Luffy frantically grabbed at his hair and protested loudly.
"These things weigh at least tens of thousands of pounds! And that chain..."
He cautiously touched the black chain with one hand. An extremely strange sense of weakness instantly spread through his entire body, making his legs go limp as he dropped straight to his knees.
"This is Seastone! I'm a Devil Fruit user! I can't even use a bit of strength when I touch this stuff! How am I supposed to lift it?!"
Monkey D. Luffy looked like he was about to cry. This was simply an impossible task.
Ace was not a Devil Fruit user, but the sight of those mountain-sized sea beasts still made his scalp tingle.
"Impossible? That word doesn't exist in my dictionary."
Lei En sneered, and a deep-blue whip formed in his hand, made entirely of pure high-voltage lightning.
Crack!
The lightning whip snapped sharply through the air, filling the atmosphere with the pungent smell of ozone.
"If you don't push yourself, how will you break through the side effects of your Devil Fruit?"
Lei En looked down coldly at Monkey D. Luffy, who lay sprawled on the ground.
"Devil Fruit powers are only support. A true powerhouse relies on a body that breaks through its limits and on Haki!"
"A little Seastone turns you into a limp noodle? When you reach the New World and meet those monsters proficient in Armament Haki and Seastone weapons, all you can do is wait to die!"
He lashed out with the lightning whip in his hand, mercilessly striking the sand beside Monkey D. Luffy and Ace and blasting a charred crater into the beach.
"Stop making excuses! Wrap those chains around yourselves!"
"Run ten laps around Mount Colubo carrying that weight! If you don't finish, neither of you gets to eat today. You'll both receive a Million-Volt Baptism!"
Faced with Lei En's utterly deranged coercion, Monkey D. Luffy and Ace did not dare utter another word of refusal.
They gritted their teeth and used the last trace of strength in their bodies to wrap the heavy Seastone chains tightly around their shoulders.
"Grah—!"
The moment they stood up, the terrifying weight made their legs tremble violently, and their knees nearly shattered under the pressure.
Monkey D. Luffy had it especially bad. The weakness radiating from the Seastone made him feel as though every bit of strength had been drained from his body, making even breathing exceptionally difficult.
But he knew that if he stopped, an electric shock a hundred times worse than this pain awaited him.
"I... I'm... going to become the King of the Pirates!"
Monkey D. Luffy let out an unwilling roar, his eyes bloodshot.
Relying purely on the muscle memory Lei En had beaten into him over the past week, along with an overwhelmingly stubborn refusal to lose, he dragged the enormous Sea King and took the first step with extreme difficulty.
"One step... two steps..."
Ace refused to be outdone. A blazing fire burned in his lone-wolf eyes as he followed close behind Monkey D. Luffy.
The two small figures carried sea beasts as heavy as mountains through the rough, steep terrain of Mount Colubo, beginning an incomparably tragic "crawl."
Every step left a deep footprint in the ground.
Sweat struck the dirt like raindrops, mixed with the blood flowing from their chafed and torn skin.
Lei En sat at the edge of the cliff, biting into an apple as he watched the two figures below inch along as slowly as snails without ever giving up.
His Observation Haki sensed it clearly.
Under such extreme physical strain and the oppression of Seastone, the enormous potential long hidden within Monkey D. Luffy and Ace was being ruthlessly forced out and awakened at a volcanic pace.
Monkey D. Luffy in particular—his rubber cells, continuously weakened by the Seastone, had begun developing an extremely bizarre resistance mutation in order to keep his muscles functioning.
The foundations of his basic combat skills and strength were skyrocketing at a monstrous rate.
"At this pace..."
Lei En tossed away the apple core and clapped his hands in satisfaction.
"In half a month at most, I can officially teach them how to use Armament Haki."
Just then, Lei En's keen hearing suddenly caught an incredibly faint disturbance coming from deep within the forest.
"Rustle..."
It sounded like someone was cautiously drawing closer.
And whoever it was hid their presence extremely well. If Lei En's Observation Haki had not been so absurdly powerful, he likely would not have noticed.
"Oh? Another rat has sneaked in?"
A teasing sneer curled across Lei En's lips. He did not turn around, merely leaning lazily against the rock.
"Since you're here, stop hiding."
His voice was not loud, yet it clearly carried through the forest.
"Let me guess. Did you come to collect these two brats' corpses, or... did you come looking for a fight with me?"
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