Jack quickly returned to his original body size.
Even so, he still stood more than eight meters tall.
The muscles across his body became even more solid, and his head still retained the shape of a mammoth.
"An awakened Zoan fruit… a human-beast hybrid form?" Renji narrowed his eyes slightly.
It was clear that Jack had been forced into his final form.
This form also happened to be the best one for Renji to "farm."
The mammoth form was powerful, but its speed was far too slow. Every attack required a long preparation.
This hybrid form was different. It might be slightly weaker in pure strength, but it was far more balanced.
"Smart choice," Renji said calmly.
A cruel smile appeared on Jack's mammoth-like face.
Black-purple Armament Haki wrapped around both of his fists.
"This will be the last thing you see."
The moment he finished speaking, Jack's fist shot forward toward Renji.
Compared to the mammoth form, this attack was much faster.
"Die!"
"Perfect!"
This time, Renji did not use the Tremor-Tremor Fruit that could threaten Jack directly.
Instead, his own fists were wrapped in Armament Haki as he met the attack head-on.
BOOM!
A dull impact echoed.
Their fists collided.
For a moment, Renji was suppressed.
"Hahaha!"
Seeing this, Jack burst into laughter and pushed forward again.
BOOM!
Another heavy impact rang out.
Renji was forced to step backward several paces.
In terms of raw strength, even with the reduced power of his hybrid form, Jack was still stronger than Renji.
[You picked up 1 Devil Fruit Growth Experience!]
[You picked up 1 Strength!]
Renji immediately showed an annoyed expression on his face.
"Again!"
As if unwilling to accept defeat, Renji rushed forward once more.
Both fists were wrapped in thick Armament Haki, and the wind from his punches howled sharply.
"Good!"
Jack naturally welcomed the challenge.
BOOM!
Another clash of fists.
The sheer force shook the deck beneath their feet.
[You picked up 1 Devil Fruit Growth Experience!]
[You picked up 1 Agility!]
The next moment, Renji was sent flying again.
At this point, Renji seemed to have completely lost his sense of strategy.
Like a reckless brute, he stared at Jack with bloodshot eyes and shouted, "Again!"
His strength gathered once more.
This time, his power was even greater than before.
"Then come again!"
Jack showed no hesitation and charged forward.
During this exchange, Jack began to notice that Renji's strength was gradually increasing.
However, it was still within the range he could handle.
"Ha!"
With a furious roar, Jack unleashed another burst of power.
Renji was sent flying once again.
[You picked up 1 Strength!]
[You picked up 1 Strength!]
Two more attributes.
Inside, Renji was overjoyed.
These were not ordinary attributes. They were attributes from a Yonko commander-level opponent.
Almost every time he collected them, Renji could clearly feel his strength increasing.
Even if the increase was only around 0.0-something percent each time, Renji himself was already at the Yonko commander level.
Even when training with all sixteen hundred members of the Whitebeard Pirates, his daily growth would not exceed 0.1 percent.
But just exchanging a few blows with Jack could equal an entire day of training.
If this continued for several hours, he might not reach the peak commander level of Marco yet, but catching up to veteran commanders like Jozu would absolutely be possible.
"Again!" Renji shouted, staring at Jack with bloodshot eyes, his face flushed as if he had been greatly wronged.
Seeing this, Jack became even more excited.
"Angry? Strength is the only thing that matters!"
[You picked up 1 Strength!]
[You picked up 1 Intelligence!]
"Not satisfied? Then fight again!"
[You picked up 1 Strength!]
[You picked up 1 Devil Fruit Insight!]
"No, that last move doesn't count!"
[You picked up 1 Armament Haki Insight!]
[You picked up 1 Observation Haki Insight!]
As time passed, Jack gradually began to feel that something was wrong.
Renji looked like he was being beaten badly.
Yet he never used his Devil Fruit ability.
BOOM!
After another clash of fists, Jack panted heavily while staring at Renji.
"What exactly are you trying to do?"
At this moment, seven hours had passed since their battle began.
Even Jack, a fish-man with immense stamina, was reaching his limits.
Every exchange looked like Jack had the advantage.
Every exchange seemed to send Renji flying.
Yet Renji always got back up.
His stamina felt like a bottomless abyss.
[You picked up 1 Strength!]
[You picked up 1 Agility!]
"What, are you scared now?!" Renji taunted. "Coward! If you're scared, then just stand there and let me beat you!"
Renji ignored Jack's question completely.
After seven hours of fighting, his overall strength had already increased by about five percent.
That kind of growth would normally take months aboard the Moby Dick.
His Armament Haki and Observation Haki had also improved dramatically.
Renji could now use advanced Armament Haki coating proficiently.
The only reason he had not used it yet was because he still wanted to keep farming attributes.
"Who the hell said I was scared?!" Jack roared angrily. "Die!"
This time, Jack attacked first.
[You picked up 1 Strength!]
[You picked up 1 Observation Haki Insight!]
"I refuse to believe you can keep getting back up!"
[You picked up 1 Strength!]
[You picked up 1 Agility!]
"You're still coming?!"
[You picked up 1 Intelligence!]
[You picked up 1 Armament Haki Insight!]
"Why aren't you attacking anymore?"
Another seven hours passed.
By now, night had fallen.
The pirates of the Mammoth Pirates and the Fourth Division had long since finished their own battle.
The two sides were evenly matched, but because Renji had trained his men relentlessly, the Fourth Division ultimately gained the upper hand.
Looking at Jack lying on the ground in front of him, Renji showed a helpless expression.
Such a perfect "experience monster" had actually been used up.
"Impossible…" Jack muttered weakly.