"Boss?
"What worked?" Tesoro, who was doing push-ups, turned to look at Roy curiously.
"Tesoro, quick, try out the new ability I just developed."
Without waiting for Tesoro to get up, Roy enveloped him in the Gravity Domain.
"Thump!"
With a soft thump, the completely unprepared Tesoro was instantly slammed into the ground by an invisible force, sending dust flying.
"How does it feel, Tesoro?"
Tesoro felt as though a small mountain were pressing down on him. Every bone in his body trembled, and he could barely move a finger.
"B-boss... what is this..."
Seeing Tesoro lying helplessly on the ground, his face flushed red from the strain, Roy looked embarrassed for a moment. He hurriedly adjusted the gravity acting on Tesoro, bringing it down to the maximum he could bear.
"How about now, Tesoro?"
Tesoro struggled to raise his head. Sweat quickly covered his forehead, and the veins in his arms bulged as he gritted his teeth.
Under twice the normal gravity, movements that were usually effortless had become incredibly difficult.
"This... is... amazing! But... boss, what exactly is this?" Tesoro asked through gritted teeth as he slowly rose to his feet.
"Hehehe!"
"Gravity. For now, I'm calling it the Gravity Domain. Inside my domain, I can adjust the strength of the surrounding gravity however I want. Isn't it much better than your ordinary weight training?"
Roy was excited. With the help of gravity, his companions' strength should improve rapidly, so he wouldn't have to worry about them in future battles.
Watching Tesoro's plight from the side, Stella and Savi couldn't help swallowing. They looked at Roy with a little more awe, as though they already knew what awaited them.
Roy smiled, and the domain instantly enveloped the other two. He adjusted the gravity on them little by little,
until they could still move, but only with great difficulty.
In the days that followed, training on the back mountain entered hell mode.
Roy was no longer satisfied with simple physical sparring and guidance in Haki.
He set up several challenges within his domain: a zone of triple gravity extending three hundred meters around him, a zone of double gravity extending another five hundred meters beyond that, and a zone of normal gravity extending another thousand meters, where Savi trained.
He also occasionally changed the direction of gravity in an instant while they trained, creating chaotic gravitational turbulence to improve their ability to react. He kept the gravity active even while they ate and slept, helping them quickly adapt to its strength.
Tesoro received particular attention.
Roy knew Tesoro had considerable potential, but compared to him and Bullet, Tesoro's foundation was still too weak. If he didn't work hard now, he would only reach the level of Kaido's All-Stars in the future.
So Roy focused his attention on Tesoro. After all, he was Roy's first subordinate!
Under gravity's relentless battering, day after day, Tesoro's physical strength grew at an astonishing rate, and his control over his own power became more refined. More importantly, his will grew tougher with every struggle at his limits.
Stella and Little Savi were no exceptions. As they adapted to the gravity, both their physical capabilities and their ability to adapt to abnormal environments improved rapidly.
A year had now passed since Roy arrived on the island.
Roy was now twelve years old and had grown to two meters tall. His long golden hair hung loose down his back, and he wore a black suit. His streamlined muscles were not only pleasing to the eye, but the strength they contained was not much inferior to Bullet's.
Since Roy developed the Gravity Domain seven months ago, the entire group had grown astonishingly stronger.
Roy could now cover his entire body in Armament Haki. His swordsmanship had made little progress, though he could imbue his slashes with his ability. As for how to reach the realm of a swordmaster, he was still completely in the dark.
His Conqueror's Haki, on the other hand, had gained greater suppressive and destructive power thanks to his mental strength.
With his current strength, he could deal with ordinary Vice Admirals without any difficulty.
Tesoro had also mastered the Six Powers, and both types of Haki had awakened under Roy's guidance. Though they worked only intermittently, as long as he continued training at his current pace, he should be able to use them proficiently before long.
Stella continued developing ways to combine her Devil Fruit ability with the Six Powers, forming her own fighting style. The awakening of Observation Haki made him more sensitive to changes in the surrounding magnetic field and weather.
To Roy's greatest surprise, Savi had gritted his teeth and endured the high-intensity training. Comparatively speaking, his strength had grown the fastest of the group.
After Roy developed gravity training, Bullet tried it a few times and began visiting more frequently.
Roy had taught him how to train his Haki early on, so he was already far stronger than he had been at the same point in the original story. The title of Demon Heir had also spread across the battlefield!
After spending so much time with Roy and the others, Bullet no longer wore a sour expression all day like he had when they first met. He would occasionally tell them about things that happened in the army, and he gave little Savi the most "attention."
As he explained it, he was afraid that Savi would be too weak in the future if he followed Roy, and would be killed when he encountered an enemy.
Recently, however, he had returned to how he had been when they first met. Once he arrived, he would mechanically perform physical training that bordered on self-abuse under Roy's triple gravity-push-ups, squats, striking massive trees...
Once exhausted, he would silently leave the camp and return to the barracks.
Everyone noticed. Roy knew he must have been betrayed by his comrades again.
"Boss, Bullet..." Tesoro said worriedly.
"Don't worry about it, Tesoro. The time for him to make his decision is drawing near. All we have to do is wait," Roy said slowly, watching Bullet leave in silence.
"When your loyalty is betrayed by your country, what decision will you make, Heir of the Demon, Douglas Bullet?!"
Meanwhile, in the conference room at the center of the barracks, Douglas Gray, a man in his forties with a sinister face, was assigning combat duties for the next phase. When he looked at the distracted Bullet in the corner, flashes of cold light appeared in the eyes of his already sinister face, but he quickly concealed them.
"Fellow officers, this time we will launch an all-out offensive, utterly defeat the other two nations, and end the centuries of war on this island. When that happens, you will all become nobles of this country and enjoy great power."
The entire conference room erupted with excitement as the generals reveled in thoughts of the power and wealth they would soon receive.
Only Bullet silently left the conference room after receiving his assignment.
He did not know that, as he left, a sinister gaze remained fixed on his back.
After the meeting ended.
"General, Bullet's movements have been very suspicious lately. And... his strength has grown too quickly over the past six months."
General Gray's trusted staff officer reported to him after everyone else had left.