On the deck of the Going Merry.
Kai swept his gaze over everyone, first looking at Nami and Usopp.
He shook his head, a hint of helplessness in his voice: "The two of you have such a poor foundation; you haven't even reached the threshold of the Body Tempering Technique."
"W-what?!" Nami's eyes widened, her face filled with disbelief. "I exercise every day! How could I not have reached the threshold?"
Usopp also panicked, quickly shouting, "Exactly! I'm the strongest sniper; there's nothing wrong with my physical condition!"
"Stop making excuses," Kai snorted coldly.
"Starting today, your physical training will be doubled. Running, push-ups, weighted exercises... everything will be increased.
Additionally, try to practice Observation Haki. Although there won't be any results in the short term, the training of mental fortitude cannot be neglected."
Nami and Usopp immediately wailed, "This is going to kill us!"
Regarding the training of mental fortitude, it still requires being baptized by Kai's Conqueror's Haki, just like before.
Kai is responsible for precisely controlling and oppressing everyone with Conqueror's Haki, while Luffy chooses to use Conqueror's Haki for defense, covering everyone.
This way, everyone can get sufficient mental training, and the intensity can be adjusted at any time.
Kai ignored their complaints and turned to look at Luffy, Zoro, and Sanji:
"For the three of you, your training plan will continue with daily mental fortitude exercises and the Body Tempering Technique.
However, the training of Armament Haki and Observation Haki must proceed simultaneously.
Additionally, 'Moonwalk' from the Six Powers is a mandatory skill.
Especially for Luffy, your shortcomings are too obvious. Moonwalk can make up for your deficiencies, and this is a key point."
Luffy scratched his head, his face full of confusion: "What's Moonwalk?"
"Simply put, it allows you to walk in the air," Kai explained patiently.
"There are countless strong individuals on the Grand Line, and some places you can't reach with your Gum-Gum Fruit ability.
For example, the sea. You're a Devil Fruit user; falling into the sea means you're finished.
Mastering Moonwalk can greatly increase your flexibility and prevent you from being restricted by terrain."
"Wow! Walking in the air! That sounds so cool!" Luffy's eyes instantly lit up, eager to try. "I definitely have to learn it!"
"Don't get too excited too soon," Kai said coldly.
"Moonwalk training is very difficult. Without strong physical support, you won't even grasp the basics."
At this point, Kai took something out of his pocket—a metal fragment with a cold gleam, the remnant of the Sea Prism Stone from Smoker's jitte tip.
Kai had deliberately collected it when he severed Smoker's jitte, intending to train Luffy's resistance to Sea Prism Stone.
"This is..." Zoro's gaze narrowed, and he said in a low voice, "Sea Prism Stone?"
"That's right," Kai nodded. "I specifically collected it in Loguetown. Luffy, this is for you."
"For me?!" Luffy looked surprised. "Are you kidding me! This thing will make me completely powerless!"
"Precisely because of that, I'm giving it to you," Kai handed the Sea Prism Stone fragment to Luffy, his gaze stern.
"If you want to become the King of the Pirates, the strongest in the world, you cannot have any weaknesses.
A strong person's weakness will be infinitely magnified in the eyes of other strong people. At that time, your weakness will kill you."
Luffy opened his mouth, wanting to retort, but seeing Kai's stern expression, he ultimately closed it.
He took the Sea Prism Stone fragment, and immediately felt all his strength drain away as if it had been sucked out, and he collapsed directly to the ground.
"Ah... I can't... I can't move!" Luffy wailed loudly, his face a picture of misery.
"Get up and try!" Kai barked coldly.
"Practicing the Body Tempering Technique in this state can yield twice the results with half the effort.
You must learn to adapt to the suppression of the Sea Prism Stone until you can ignore its effects!"
Luffy's face was full of reluctance, but he finally gritted his teeth and stood up.
His legs trembled as he painstakingly adopted the posture of the Body Tempering Technique and began his training.
"What a madman..." Sanji sighed, then turned to Kai. "But, the madman actually has a point."
Zoro nodded, a cold smile playing on his lips: "Quite interesting. I'd like to see how long this guy can last."
Nami and Usopp, however, watched Luffy struggling on the ground with horrified expressions, seemingly foreseeing their own futures.
On the deck, Kai stood with his back to the sun, his gaze coldly sweeping over Zoro, Sanji, and Luffy.
He tightened his grip slightly on the Fangtian halberd, his tone calm yet unyielding.
"The three of you, listen carefully. The upcoming training must be done with all your might.
After one round of the Body Tempering Technique, the focus will be on Armament Haki and Observation Haki, especially Armament Haki."
Kai's voice was deep and powerful, as if every word carried immense pressure.
"You wouldn't want to be suppressed and beaten by a Logia user again, like in Loguetown, would you?"
Luffy scratched his head, his smile gradually stiffening.
Zoro gripped the swords at his waist, his gaze slightly darkened, and a hint of unwillingness flickered across his face as he recalled Smoker.
Sanji exhaled a smoke ring, remaining silent, but his slightly bowed head clearly indicated everything.
"Being suppressed by a Logia user with no power to fight back, don't you think that's a very shameful thing for you?"
Kai's gaze swept over the three of them, his voice growing even deeper.
"On the Grand Line, there are many Logia users like Smoker.
If you can't even defeat opponents like that, what's the point of chasing your dreams? What's the point of becoming the strongest?"
Luffy's smile completely vanished, his head hanging low, his fists clenched tightly, his knuckles making faint cracking sounds.
A hint of shame appeared on Zoro's face. His lips were tightly pressed together, and his eyes held a burning, unwilling anger.
Sanji put out his cigarette, looked up at Kai, his eyes more serious than usual: "Kai, how should we train Armament Haki?"