It was a strange talent.
Rengoku found the pink-haired boy in front of him quite fascinating.
"Quite remarkable, Coby!"
"R-Really? Thank you, sir!"
The sudden praise(?) from Rengoku left Coby stunned these days.
"How could one's talent be so concentrated in their legs?"
It was something Rengoku had noticed since Coby first enlisted—his lower body was unusually well-trained.
"Did you happen to be a runner or an athlete before joining the Navy?"
"N-No, nothing like that!"
"But from the very start, your legs were well-developed. And now, after your Navy training, they've only grown stronger!"
At Rengoku's words, Coby recalled his past, back when he had been a coward who only knew how to run away.
Could it be… that all that running somehow trained his legs without him realizing?
Meanwhile, Rengoku admired Coby's sturdy calves, yet something still felt off.
"With lower body strength like that, you should naturally be specialized in kicks. So why are you so fixated on punches?"
Coby's leg strength was now on par with the Longleg Tribe. With such power, being kick-focused would be expected. And yet, Coby's main fighting style involved his fists.
When the Vice Admiral pointed out this "fixation,"
Coby instinctively recalled a certain boy…
A boy with a straw hat.
And his bullet-like punches.
"T-That's… a promise of mine."
Not wanting to bring up pirates in front of Rengoku, Coby gave a vague but honest answer.
Hearing this, Rengoku nodded understandingly and shifted the topic.
"Have you mastered the technique of combining Iron Body (Tekkai) with fluid movement in Rokushiki?"
"Yes!"
Seeing Coby respond with such confidence brought a satisfied smile to Rengoku's face.
In his previous life, all of his Tsuguko (successors) had given up because the training was too intense.
This world was far more physically extreme than Earth, but even here, Coby had improved beyond the level of a typical naval officer.
"Then how many dans have you been awarded in Fish-Man Karate?"
Rengoku had just received his 100th dan in Fish-Man Karate from a certified master a few days ago, and asked Coby as a side thought.
Coby, who was already well aware that Rengoku had over 200 dans across both Fish-Man Karate and Jujutsu, scratched his head shyly and replied:
"I… I just reached 40 dan recently. It's nothing compared to you, sir… hehe."
"Excellent! I've been training since I was a child, but you enlisted midway—and yet you've achieved 40 dan already. That's a result of both your hard work and your talent!"
The officer of the Arlong Pirates—once considered the strongest group in East Blue—Kuroobi, held a 40th dan in Fish-Man Karate.
Given Kuroobi's performance, it might not seem like much, but the fact that a human who had only trained for just over half a year reached the same level as a Fish-Man who had trained for at least 20 years was a truly astonishing display of talent and effort.
"Can you tell me which technique you're best at in Fish-Man Karate?"
"Ceiling Tile Straight Punch, sir!"
The most basic straight punch—yet that was the one he had mastered best.
An obsession with punches.
Leg strength comparable to the Longleg Tribe.
The ability to use Tekkai and Soru simultaneously…!!
"Then today, I'll teach you the application of Total Concentration Breathing!"
"Th-The application, sir?"
"Yes! There are five foundational schools of Total Concentration Breathing. Among them, your body is best suited to the Breath of Thunder!"
The Breath of Godspeed—a style that could only be used with a heavy, powerful lower body!
This style was well-suited for Coby, who could already combine Tekkai with high-speed movement.
However, as with all breathing styles, there are two types of compatibility to consider:
1. Breath compatibility
2. Form compatibility
Some individuals may be compatible with, say, Water Breathing, but not have the form compatibility to master more than one technique—only ever able to use the First Form: Water Surface Slash.
Others are compatible with both breath and form—such as Giyu Tomioka, the Water Hashira.
And then there are monsters of talent who are compatible with Flame Breathing, but also miraculously possess form compatibility with multiple other styles—Rengoku being one of them.
Coby's body was physically well-matched to Thunder Breathing, but Rengoku was curious about whether he had form compatibility as well.
Thus, Rengoku began to teach Coby the breathing principles and techniques of Thunder Breathing, and demonstrated the six known forms he had mastered.
Though Coby wasn't a swordsman, forms weren't restricted to blade-users.
Just like how Stone Breathing is typically for swordsmen, yet Gyomei Himejima used a flail and axe instead.
...
"Your talent is truly remarkable!"
"Y-You think so?"
"But why do you only show compatibility with the First Form: Thunderclap and Flash?"
It was similar to the boy Zenitsu Rengoku had known back on Earth.
But it was still more than enough.
"When you use Thunderclap and Flash, you must simultaneously activate Soru and Tekkai, strengthen both hands with Armament Haki, and grip your right wrist tightly with your left hand!"
The explosive dash of Soru, combined with Thunderclap and Flash, which focused power into the legs.
This combination would be devastating.
It would turn Coby into a human railgun.
Given the immense speed, even with Armament Haki, the strain on the wrist could cause injury—so applying double reinforcement was necessary.
"This will become your ultimate technique! Train it well, and keep refining it through constant effort!"
Coby responded with a thunderous shout of determination.
"Prinprin! I'll leave Coby's training to you from now on!"
Rengoku assigned the task to Prinprin, whom he hadn't seen in a while.
Prinprin had grown stronger in the past few months.
Though still only at the Brigadier level, Prinprin wielded the Kashuu, one of the 50 Skillful Grades Swords.
He had no compatibility with any form of Total Concentration Breathing.
But his proficiency in the breathing techniques themselves and Rokushiki was top-tier, and his combat sense and experience were far beyond what someone like Coby could hope to match yet.
Entrusting Coby's training to someone like that would surely result in tremendous growth.
"Understood!"
Prinprin, excited by Rengoku's command, was more than ready.
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