"Oh, right."
Zephyr's tone shifted as he gave a serious reminder.
"As for the electrotherapy stimulation method… I personally recommend you don't exceed three hours a day. Otherwise, your body may not be able to handle it."
"Even if your physique is strong…"
"If you take too many rounds of current stimulation, it can still leave irreversible hidden injuries and long-term risks."
"So don't mess around."
"I don't want to hear bad news about you someday. If that happens… that bastard Garp will probably come looking for me with those iron fists."
Hearing that, Kai nodded.
"Don't worry, Instructor Zephyr. I know my limits."
He wasn't stupid enough to gamble with his own body.
Moderation—those four words—he understood perfectly.
Once you exceeded what the body could endure, the damage could become irreversible.
Of course…
With the Ghost Back System, Kai could use the 100x training effect to forcibly repair some hidden damage after each session.
So he didn't need to be as cautious as Zephyr made it sound.
"Good. Since you understand, I won't explain further."
Zephyr patted Kai's shoulder, ready to leave.
Then he turned to the researchers not far away and issued a stern order.
"From today on, this brat is living here."
"Listen up—take good care of him."
"Don't let him do anything reckless."
"If something happens to him…"
"Even if I don't come after you, plenty of people will."
"This kid is the Marines' precious treasure right now."
The researchers immediately nodded.
"Admiral Zephyr, rest assured. We'll take care of Mr. Kai. We absolutely won't let him train recklessly."
"Good."
Zephyr looked satisfied.
After giving Kai a few more instructions, he turned and left the sealed chamber alone.
Kai watched Zephyr's back until it disappeared, then slowly withdrew his gaze.
"Come on."
"Let's keep going."
He turned to the research team leader beside him.
The team leader froze.
"Uh… Mr. Kai, are you sure you don't want to rest?"
"You just came out of the capsule…"
"It's only been a few minutes, and you want to go again?"
That was insane.
Was every Marine in this era this… brutally competitive?
The team leader gave a bitter smile.
"Admiral Zephyr just said that if you overuse electrotherapy stimulation, it might leave hidden injuries and risks."
"Mr. Kai… please don't make things difficult for us."
"It's fine." Kai waved his hand.
"My body—I know it best."
"You just do what I tell you."
"If anything goes wrong, I'll take full responsibility."
"Enough talking."
The next second, Kai stepped forward and entered the capsule again.
Thunk.
The door sealed shut.
Outside, nearly ten researchers exchanged helpless, bitter looks.
"Captain… what do we do?" someone asked weakly.
They couldn't disobey Zephyr.
But they also didn't dare disobey Kai.
They were trapped.
The team leader thought for a moment, then spoke decisively.
"Start the stimulation, but keep watching Mr. Kai's condition."
"If anything looks even slightly wrong—stop immediately."
So, under their control…
The electrotherapy stimulation began again.
Zzz—zzz—zzz!
Currents surged into the capsule, flooding the interior—
And Kai once again tasted that strange mix of pain and pleasure as scorching heat swept across his whole body.
The currents were like sharp steel needles, continuously piercing his skin.
And not only that—
Even the air he breathed carried currents into his body, tempering his organs, meridians, bones, and blood.
"The feeling of becoming stronger…"
"It's intoxicating."
Kai closed his eyes, a look of pure enjoyment on his face.
Every strand of current that merged into him brought a sensation of explosive growth.
In this special environment—
His strength climbed steadily.
Every minute, every second—
His power leapt upward.
This extreme electrotherapy method truly felt tailor-made for Kai.
And with his Ghost Back System's 100x amplification…
The effects of electrotherapy were multiplied again.
That was the real reason Kai could feel his strength skyrocketing.
If he didn't have the 100x boost…
Even electrotherapy wouldn't let him grow this fast.
To put it simply—
The core reason for Kai's explosive growth wasn't the electrotherapy capsule.
It was the Ghost Back System.
That was all.
The capsule was merely a tool—an assistant.
Kai's growth wasn't something others could copy.
If anyone else entered the capsule, they would never experience this "every second" leap in power the way Kai did.
Only Kai.
One of a kind.
Across the entire sea, only he was this unique.
Watching the five-year-old inside the capsule wearing a blissful expression while being tortured by intense currents—
The researchers were shaken to the core.
They stared at him like he was a monster.
"Mr. Kai…"
"He's terrifying," one researcher said hoarsely, throat dry.
This was the first time they'd seen someone suffer extreme pain from current stimulation—
And still look drunk on it.
The team leader swallowed and muttered in awe.
"What a training maniac…"
A genius like Kai—so insanely gifted, yet also this insanely hardworking—
It was the first time they'd ever even heard of someone like that.
"Not only is his talent heaven-defying…"
"His willpower is terrifying too."
"And his discipline is even more frightening."
"He trains hundreds of times harder than normal people…"
"With a genius like that…"
"How could the sea's monsters not despair?"
"This era producing a monster like Mr. Kai…"
"He's going to become the psychological shadow of every so-called genius!"
A hardworking genius was the most hopeless kind of opponent.
He was already born ahead of everyone—
And now he poured in effort and sweat that dwarfed everyone else.
If that kind of person didn't become stronger…
Then the world had no rules.
From that day on, Kai moved out of his old residence and officially settled inside the Marine Research Institute.
After that—
Marineford rarely heard news of him again.
In the days to come, almost no one saw Kai.
Gradually, he seemed to vanish from the world.
It made many Marines curious…
But no one dared dig too deep.
Only the Marine high command knew the truth:
Kai had entered closed-door, isolated training.
It was boring.
It was monotonous.
But Kai never grew tired.
Across all of Marine Headquarters, only the trainees from Zephyr's camp still thought about him every day—the prodigy who had crushed them with overwhelming strength.
Smoker, Tina, and the rest of the elite trainees trained even harder, taking "catching Kai" as their goal.
Even if they didn't know why Kai disappeared—
They were certain of one thing:
When he appeared again…
He would be far stronger. Far more terrifying.
So they couldn't fall behind.
They had to chase.
Even knowing—
They weren't qualified to keep up with that monster's footsteps…
They still poured out their youth and sweat for it.
Marineford's atmosphere turned fiercely positive.
"Kai—next time we meet, the strength I show you will shock you!"
"Just you wait!"
"I won't lose to you by too much!"
Smoker's eyes were full of steel.
Meanwhile, Tina's heart was filled with admiration.
"Kai… little brother."
"I won't let you leave me too far behind."
"I'll chase your footsteps."
"Stand beside you."
"And in the end…"
"I want to be worthy of you."
It was obvious.
All the trainees worked harder than ever.
…
Time rushed by.
Stars shifted, tides rose and fell, seasons changed.
It slipped away between people's fingers—
Uncatchable. Untouchable.
All anyone could do was passively endure the scars time carved into their bodies.
And so—
Day after day.
Year after year.
In the blink of an eye—
A full year had passed.
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