One Piece: The user of the Nen-Nen Fruit, who overturned the sea.

The moment Roy's gravity field unfolded, everyone let out a muffled groan.

An invisible pressure descended like a mountain, exacerbating the already numbness in the body caused by the lightning.

Free ions in the air become more active under the influence of gravity.

The crackling thunder seemed to explode right next to my ears.

"Damn... this feeling..."

Jack gritted his teeth, his legs trembling slightly, the power of the Mammoth Fruit surging within him.

He barely managed to stay upright in the area with five times the gravity.

Runti and Paget supported each other, their legs trembling slightly.

Maria took a deep breath, her elegant posture becoming increasingly difficult to maintain, and fine beads of sweat appeared on her forehead.

Yamato adapted the fastest; she merely frowned before assuming the starting stance of a spiked club.

"Interesting! This is much more effective for cultivation!"

Kaido, feeling the pressure of gravity on his body, grinned widely.

"Hehehe... Roy, your gravity field is interesting! I haven't felt this 'heavy' in ages!"

The flames behind Jin flickered slightly, seemingly adapting to the dual environment of gravity and lightning.

"This kind of cultivation environment is truly unprecedented."

On Roy's side, everyone was also adapting.

Savi grimaced and moved his limbs, while Enel and Pea began to try to move under the influence of lightning and gravity.

Moria's massive body appeared even more cumbersome under gravity.

But a determined light shone in his eyes—he knew this was an opportunity to become stronger.

Vera was pale, but she stubbornly straightened her back.

Stella closed her eyes and concentrated, beginning to try using the Life Return technique to adjust her physical condition.

Charon assumed a Fishman Karate stance, feeling the effect of gravity on his moves.

"Let's begin."

At Roy's command, everyone immediately sprang into action.

In the outer areas, lightning is relatively sparse, and the gravitational force is between 1 and 5 times stronger. This is the most suitable place for beginners to get used to the environment.

Stella, Savi, Enel, Pea, Charon, Moria, and Vera remained here.

Their primary task is to control the return of lives—a hard target set by Roy.

"Concentrate and feel every part of your body."

As the only one among them who possessed the ability to restore life, Savi took the initiative to guide the others.

"Imagine you can control the peristalsis of your internal organs, the flow of blood, and even the respiration of your cells..."

He explained and demonstrated at the same time.

To everyone's astonishment, Savi's body slowly turned red, and wisps of heat rose from it.

"Life restoration not only accelerates recovery, but more importantly, it allows us to achieve the ultimate control over our bodies."

This control is especially crucial in gravitational fields and lightning strike conditions.

Stella and the others sat down cross-legged and closed their eyes to try it.

Enel possessed a natural talent for Observation Haki, which also meant that his mental strength was stronger than that of ordinary people.

In addition, his physique has been continuously improved under Barrett's training.

Enel quickly figured it out.

The pea plant itself is particularly sensitive to life energy, second only to Enel in terms of progress.

Charon's fish-like physique naturally gives him abundant life energy, making his studies twice as effective with half the effort.

Despite his enormous size, Moria's progress was not slow due to the physical strength of the Oni race.

Of all the people in the arena, only Vera, who relied entirely on her "Venom-Venom Fruit" ability to fight, had the weakest physique.

Returning to life requires physical strength and extreme control over the body, which is quite difficult for her.

"Don't rush," Stella said, walking to her side.

"First, improve your physical strength in this environment and then practice the Six Forms."

"Roy said we'll be staying here for quite a while, so we have plenty of time."

Vera nodded, took a deep breath, stood up, and began basic physical training.

In the middle layer, gravity is 6-10 times stronger, and thunder is as dense as rain.

This place is home to Jack, Ulti, Page One, Maria, and Yamato, who took the initiative to delve deeper.

All five are Zoan-type Devil Fruit users, possessing formidable physiques and endurance far exceeding that of ordinary people.

Jack chose the most violent training method—to endure it head-on.

He immediately entered his human-beast form, his mammoth-like thick hide and muscles trembling under the combined pressure of gravity and lightning.

But he gritted his teeth and pounded the ground with each punch, honing his Armament Haki.

"Not enough! Not strong enough!"

Jack roared, sweat and blood streaming down his body, only to be evaporated by the lightning.

Runti and Pageman's methods of cultivation are completely different.

The siblings stood back to back, with Runti on defense and Pageman on counterattack.

Runti's headbutt is hardened with iron, and its power increases rather than decreases under gravity;

Page Van's finger gun became even more precise under the stimulation of lightning, each strike shattering a bolt of lightning.

"Sis, top left!" Page Van shouted in a low voice.

Runti suddenly ducked, and with a headbutt, she shattered the incoming lightning.

At the same time, Page One fired his finger gun, shattering another bolt of lightning, and the siblings' teamwork became increasingly seamless.

Maria's training method was the most unique. She did not rush to go deeper, but instead steadily advanced in the area with six times the gravity.

Every step was taken with extreme steadiness, and every breath was adjusted to the optimal state.

She is adapting, observing, and searching for the rhythm that suits her best.

Yamato is undoubtedly the most dazzling of the five.

This little girl seems born for battle; Kaido's bloodline makes her...

It thrives under the pressure of gravity and thunder.

"drink!"

With a shout, Yamato swung her spiked club "A-Jian," creating a sound like thunder and lightning.

She has already mastered the basics of the Six Styles. Although she is still quite inexperienced, each attack carries an awe-inspiring power.

"My father always said that in battle, you have to go all out!"

With fighting spirit burning in his eyes, Yamato swung his bat and cleaved a bolt of lightning as thick as a bucket in two!

In the inner region, gravity is 10-15 times stronger, and lightning pours down like a waterfall.

There are only Roy, Barrett, Mihawk, Kaido, and King here.

Barrett chose the most violent training method—to confront the thunder head-on.

Even under fifteen times the gravity, the fully transformed white tiger's body remained as swift as lightning.

The tiger claws tore through the air, colliding head-on with the purplish-black lightning.

Hawkeye's training method is completely different. He sits cross-legged in a region with twelve times the gravity, with Black Blade Night across his lap and his eyes closed.

He is "listening".

Listen to the trajectory of thunder, listen to the flow of air, listen to the tremors of space.

The ultimate skill of a swordsman is to perceive all things and then cut them down.

In the extreme environment of Thunder Island, every lightning strike is an excellent "lesson".

Kaido and King, relying on their own talent and physical strength, frantically trained their bodies to the limit of their own endurance.

Tesoro's training method is the most unique.

He flew directly to the edge of the core lightning pool, the place where the lightning was most concentrated and most violent on the entire island.

"Come on... let me see where the limits of the Rumble-Rumble Fruit are!"

Tesoro extended his finger, and strands of deep purple, almost black lightning from the Thunder Pool were drawn into his body.

Excruciating pain! Torn apart pain!

Each bolt of lightning entering the body felt like countless sharp blades cutting through the meridians, bones, and cells.

But Tesoro gritted his teeth and persevered, knowing that this was an excellent opportunity to refine his Devil Fruit abilities and enhance his strength.

What surprised him even more was that during the process of absorbing these ancient lightning bolts,

He vaguely sensed a faint "resonance"—as if these thunderbolts contained some kind of residual will.

"The previous generation... a user of the Rumble-Rumble Fruit?"

A sudden realization dawned on Tesoro, and he absorbed the energy even more frantically.