Unknown waters of the East Blue.
The Going Merry sailed quietly across the vast ocean, its sails gently billowing.
Carried by a soft breeze, the ship slowly moved forward.
On deck, the few who had just eaten were busy with their own tasks, the atmosphere peaceful and serene.
Nami and Usopp, having heeded Kai's advice, were actively exercising.
They sought Kai's approval, aiming to meet the standards he set.
This was to earn the custom-made body tempering technique Kai promised, their ticket to becoming strong.
Luffy and Zoro were sitting cross-legged on the deck, preparing to receive the baptism of Kai's Conqueror's Haki.
This was an unconventional training to enhance their mental fortitude.
"Are you ready?" Kai looked at Luffy and Zoro.
"Ready!"
"Bring it on!"
Both men, who had been sitting cross-legged with their eyes closed, opened them simultaneously, looking at Kai with bright, keen gazes.
"Good! Very spirited!" Kai was very satisfied with their current state.
He also admired their tenacious perseverance. In Kai's eyes, both had the potential to become the strongest.
Kai stood in the center of the deck, hands clasped behind his back, his expression stern.
His gaze swept over Luffy and Zoro, who stood before him, their faces filled with excitement mixed with a hint of nervousness.
"Your mental fortitude is not strong enough, and this will become a fatal weakness in your future battles."
Kai said slowly, his voice deep yet full of oppressive power, "From today onwards, I will use Conqueror's Haki to temper your will."
Luffy scratched his head with a grin: "Bring it on, I'm not someone who falls down easily!"
Zoro clenched his fists, his gaze like an eagle's: "Bring it on, I also want to see just how powerful your Conqueror's Haki is."
Kai smiled faintly, and with a gentle step, the air suddenly solidified. An invisible pressure, like a violent storm, crushed down on the two of them.
Luffy and Zoro instantly felt an unprecedented heavy pressure.
Every breath became incredibly heavy. Luffy opened his mouth wide, trying to keep himself steady.
Zoro used all his strength to support his body, cold sweat trickling down his forehead.
"Hold on!" Kai's voice boomed like thunder:
"This is just initial pressure. If you can't even withstand this much, you will be powerless against true formidable enemies in the future!"
Luffy gritted his teeth, his fists clenched, his body trembling slightly, but he didn't take a single step back:
"I will definitely become the King of the Pirates! This kind of pressure is nothing!"
A flicker of determination flashed in Zoro's eyes, and he said in a deep voice:
"Only dead swordsmen yield; living swordsmen must be fearless!"
Time passed by second by second. Luffy and Zoro's stamina was almost depleted, but they still gritted their teeth and persevered.
Kai's Conqueror's Haki ebbed and flowed like a tide, sometimes weakening, sometimes strengthening, as if constantly testing their limits.
Just as they were almost unable to stand, Kai suddenly withdrew all pressure.
"Very good," Kai nodded, a satisfied smile appearing on his lips, "You already have the potential of strong individuals. But this is still far from enough."
"Again!" Luffy swung his fists, his face full of excitement, "This feeling is great!"
Although Zoro was already panting, he took a deep breath and straightened his body again: "As long as it makes me stronger, this little hardship is nothing."
Kai looked at the two with satisfaction, nodding inwardly.
He knew that although such special training was cruel, it could truly temper a person's mental fortitude.
"Next, we will continue with the body tempering technique to cultivate your physique.
Two hours later, we will replenish our energy, and then resume the cycle of training." Kai explained the training plan to them.
"Luffy, when I was putting Conqueror's Haki pressure on you just now, I felt that your mental fortitude has the potential for Conqueror's Haki, it just hasn't been activated yet."
"Next time, I will increase the intensity to awaken your Conqueror's Haki!"
During the process of applying Conqueror's Haki to Luffy, Kai discovered that Luffy also had the potential for Conqueror's Haki and wanted to help him awaken it.
"Really?" Luffy's eyes lit up, wishing he could awaken it right now.
"Don't rush. For now, let's continue with the body tempering technique to cultivate your physique. We'll train something else later."
Kai motioned for Luffy to calm down, as training couldn't be rushed.
"And Zoro, don't be discouraged. I've found that Conqueror's Haki is related to mental fortitude."
"As long as you train your mental fortitude to be extremely strong, you will naturally master Conqueror's Haki."
"Luffy just has this potential naturally; it doesn't mean you can't master it."
Kai, fearing Zoro might be disappointed, specifically offered a few words of comfort.
"I won't be disappointed." Zoro smiled calmly, "I will only train hard to become the strongest swordsman!"
"Conqueror's Haki is just the icing on the cake!"
Zoro was very nonchalant, completely unaffected. He only wanted to train hard and become stronger.
And so, the three of them went through another round of body tempering practice.
Luffy and Zoro indeed felt that the body tempering technique was more effective than before, proving that training mental fortitude was a viable approach.
After replenishing their energy with grilled meat, the three were fully revived and ready for the next round of training.
This time, Kai prepared to multitask, applying different Conqueror's Haki pressures to Luffy and Zoro.
"Luffy, are you ready? To awaken your Conqueror's Haki, this pressure will be even stronger than last time!"
Kai warned Luffy, telling him to be prepared.
"Bring it on! I'm the man who's going to be the King of the Pirates!" Luffy shouted, hyping himself up.
"Good! Luffy, Zoro, I'm starting now!" Kai shouted at the two.
"Bring it on!" both shouted in unison.
This time, Kai stood in front of Luffy, his gaze like a torch, fixed on Luffy.
Although most of Kai's attention was on Luffy, the pressure of Conqueror's Haki enveloping Zoro was also under Kai's control.
As Kai's Conqueror's Haki pressure gradually intensified, Luffy clenched his fists, his body trembling slightly, his forehead covered in sweat.
He gritted his teeth, facing the Impact of Kai's Conqueror's Haki head-on, yet subtly feeling an impending burst of power within him.
"Luffy, this power is not something I'm forcing upon you, but the will deep within your heart."
Kai said coldly, his voice seemingly piercing Luffy's soul.
"If you want to become the King of the Pirates, then show your true resolve! Let your mental fortitude respond to this world!"
Luffy's eyes suddenly lit up. He gritted his teeth, and memories from the past echoed in his heart.
The moment Shanks lost his arm to protect him, the trust and expectations his comrades had for him.
And that dream buried deep within his heart—to become the King of the Pirates, to stand at the pinnacle of the world!
"I am Monkey D. Luffy! I am the man who will become the King of the Pirates!" Luffy roared to the sky, his voice piercing the clouds.
In an instant, the heavens and earth changed color.
Invisible fluctuations erupted around Luffy's body, and a violent aura, like a mountain torrent, spread out in all directions.
The waves on the sea surface surged violently under the impact of this Haki, the originally calm sea stirring with ripples that gradually turned into waves several meters high.
Even distant birds lost their balance due to this pressure and fell into the sea.
The white clouds in the sky were torn apart by this Haki, and the entire firmament trembled with this power.
"This is..." Kai's gaze sharpened, but a faint smile appeared on the corner of his mouth, "Conqueror's Haki, success! Luffy!"
Luffy's eyes became fervent and resolute, and his previously bent legs straightened again.
His breathing was no longer erratic, but had become powerful and steady.
The power of Conqueror's Haki had completely integrated into his mental fortitude, becoming an inseparable part of him.
Without the recent boost from the body tempering technique, which amplified Luffy's body several times over,
even with Kai's careful guidance, Luffy would have found it very difficult to succeed.
He probably would have needed a few more years of tempering to successfully awaken it.
The moment Luffy's Conqueror's Haki swept across the heavens and earth, the other members on the Going Merry were deeply shaken by this oppressive power.
However, fortunately, when Luffy successfully awakened Conqueror's Haki, Kai precisely controlled his own Conqueror's Haki to protect Nami and Usopp.
This prevented them from being overwhelmed by the full power of Luffy's Conqueror's Haki and fainting.
Nami gripped the ship's railing tightly with one hand, while the other covered her chest, feeling the overwhelming aura that suffocated her very soul.
"This... what is this feeling? The air seems to be vibrating, and even breathing has become difficult!"
She looked up at Luffy, her pupils trembling slightly, "It's Luffy! Luffy actually... actually awakened this power too!"
Usopp, on the other hand, was sprawled on the deck, hands covering his head, almost pressing himself into the wooden planks.
He stammered, "Luffy, he... what kind of monster is he? This, what exactly is this terrifying thing? That feeling just now, it felt like my entire soul was going to shatter!"
"That idiot Luffy, he actually managed to do something like this?" Nami shook her head vigorously after regaining her composure.
A complex smile played on her lips, "He really is an incredible guy..."
"This feeling... is amazing!" Luffy raised his fist, a brilliant smile on his face.
Zoro stood to the side, staring intently at Luffy's transformation. Although his body trembled from the aftershocks of the Haki,
a strong fighting spirit emanated from his eyes: "This guy, he really succeeded... he awakened Conqueror's Haki!"
Kai slowly retracted his aura and nodded: "Good, this is the true awakening of Conqueror's Haki.
Remember, this power is not for showing off, but for your own mental fortitude and adherence to the martial way."
Luffy nodded vigorously, his eyes filled with gratitude and determination.
He knew that at this moment, he had taken a crucial step towards becoming a true powerhouse, and Kai was the important guide who helped him awaken.
As Luffy's emotions gradually calmed, the clouds in the sky slowly dispersed, revealing a clear blue firmament.
The sea returned to its calm state, and the sunlight sprinkled on the shimmering water, reflecting the figures of the few people on the Going Merry.
Kai turned and looked towards the distant horizon, saying faintly, "Remember, the path of a strong person is never smooth sailing."
"Now, begin the next round of training. No one is allowed to slack off!"
Kai's eyes narrowed as he urged the others.
The afterglow of the setting sun cast its light on them, the sea breeze gently blew, and the Going Merry sailed, swaying with the waves.
Luffy and Zoro exchanged a smile, then began practicing the body tempering technique, not wasting a single moment of their training time.