The days following their bizarre encounter with the flamboyant Mr. 2 became a brutal crucible for Kai.
The Going Merry sailed steadily across the Grand Line, but for Kai, the real battle was happening right on the wooden deck. The "Prism Split"—the desperate maneuver where he had forced his Power Watch to manifest both the Earth and Water elements simultaneously—had nearly shattered his nervous system.
He had learned a harsh truth: the watch's software was lightyears ahead of his body's hardware. If he wanted to survive the monsters of this sea, his base stats needed a massive upgrade.
Thud.
Kai's arms trembled violently, veins bulging against his skin as he struggled to push himself up from the deck. The midday sun beat down on his signature red hoodie, soaking the thick fabric in sweat. But the heat was nothing compared to the crushing, immovable weight pressing him flat.
Roronoa Zoro sat cross-legged squarely on Kai's back, his eyes closed in a peaceful meditation, adding hundreds of pounds of dead weight to Kai's single-arm pushups.
"Again," Zoro growled, his voice carrying zero sympathy.
"Bot..." Kai wheezed, his nose a millimeter from the salty planks. "Tell me... my heart... isn't actually exploding."
From the sleek orange-and-black watch strapped to his wrist, Bot's voice chimed in his mind. [System Diagnostic: Host physical parameters are spiking. Cellular regeneration is operating at 400% efficiency.]
"See?" Bot chirped. "The elemental shifts have basically primed your muscle fibers to tear and rebuild at superhuman speeds. One hour of the moss-head's 'hell-training' is giving you the gains of a month of normal workouts. Keep pushing, hotshot!"
Zoro cracked an eye open, smirking slightly before vaulting off Kai's back with terrifying agility. Kai collapsed, gasping for air like a landed fish.
"You've got weird stamina, kid," Zoro noted, crossing his arms. "Your body adapts fast. But remember, muscle is just the engine. If your mind loses focus and you drop out of your elemental forms after sixty seconds, you're just a very muscular punching bag. Instinct over raw power. Got it?"
"Got... it..." Kai groaned, rolling onto his back and staring at the sky.
[A Few Hours Later - The Galley]
During his rare moments of rest, Kai became a sponge, absorbing the twisted rules of the Grand Line from his new crewmates.
Sitting around the galley table, the atmosphere was thick with tension. They were going over the terrifying reality of the flamboyant man they had rescued from the fog a few days prior.
"I still can't believe we just danced with a Baroque Works assassin," Usopp shivered, hugging his knees.
"Mr. 2 Bon Kurei," Vivi said, her voice tight with anxiety. She looked down at a map of Alabasta spread across the table. "He ate the Mane Mane no Mi, the Clone-Clone Fruit. He can perfectly mimic the face, voice, and body of anyone he touches. And he touched almost all of our faces. Once we land in Alabasta, Crocodile could use him to impersonate any of us to tear us apart from the inside, or worse, mimic my father to start a civil war."
"It's a terrifying Devil Fruit," Nami agreed, her expression serious. She turned to Kai. "The only comfort is that Devil Fruit users have one ultimate weakness. The sea hates them. Anyone who eats one becomes a 'hammer' in the water. They lose all their strength instantly and sink like a stone. That's why Luffy is a walking liability on a boat."
"Hey! I'm a great captain!" Luffy protested from the corner, though he was currently picking his nose.
Kai looked down at his watch, rubbing his thumb over the metal casing. Bot, he thought internally. Does that curse apply to me?
Negative, Bot's voice echoed in his mind. Your abilities stem from the Power Watch's elemental cores, not a biological mutation from a local fruit. You are completely exempt from the 'hammer' curse.
Kai couldn't help but smirk. That was a serious tactical advantage.
"Still," Zoro interrupted, leaning against the wall. "Knowing his weakness doesn't help us on land. If he shapeshifts into one of us in the middle of a fight in the desert, how are we supposed to know who is real?"
Luffy stopped picking his nose. He walked over to the table, grabbed a thick black marker Nami used for map-making, and slammed it down. "Easy. We just need a secret password."
Zoro raised an eyebrow. "A password? You'd forget it in five minutes, idiot."
"Not a spoken one!" Luffy grinned, unrolling a spool of white medical bandages. "Hold out your left arms!"
One by one, under Luffy's direction, they painted a thick, bold black 'X' on their left forearms, right next to where Kai wore his Power Watch. Then, they wrapped thick white bandages over the marks, hiding them completely from view.
"There," Luffy said proudly. "That swan guy didn't see us do this. If we ever get separated, or if we think someone is a fake, we just lift the bandage. If the mark is there, we're friends. If not, we kick their ass!"
Vivi touched the bandage on her arm, tears welling in her eyes. It was a brilliant, simple countermeasure. Looking at her, Kai felt a sharp, undeniable surge of purpose. He leaned forward, meeting her gaze. "Luffy said we're partners. That means your burden is our burden. Crocodile is going down."
[Day 4 - Approaching the Kingdom of Sand]
Another four days dragged on. The weather had completely stabilized, the air growing thick, dry, and heavy with the scent of distant sand. They were incredibly close to Alabasta.
There was just one massive problem.
"Ahhh... I'm hungry..." Luffy groaned, lying flat on the deck, his tongue hanging out exaggeratedly like a dying dog.
"Isn't this all your fault?!" Zoro barked from his spot near the mast. Due to the complete lack of food, even the swordsman had been forced to pause his intense physical training.
"Ugh..." The dimwitted captain let out a pitiful wail, then slowly turned his head toward Vivi. "Hey, Vivi... just let me use Karoo as bait to catch some fish."
"Quack...!" The giant riding duck's feathers puffed up in sheer terror.
Vivi sighed, rubbing her temples. "Luffy, you can't..."
BOOM!!!
A massive explosion interrupted her. A towering column of water shot into the sky, rocking the Going Merry violently side to side.
"What happened?!" Sanji sprinted out of the kitchen, but the moment his gaze landed on the giant creature slowly emerging from the sea foam, his worry instantly transformed into a predatory gleam.
Food!
It was a sea beast several times larger than the Merry. It had the head of a massive feline and the scaled, muscular body of a fish. Covered in shimmering green scales, the monster had been knocked completely unconscious by the underwater eruption. It floated on the surface, looking like a massive, sitting duck.
"A Sea Cat!" Usopp yelled.
"I haven't eaten in four days! Finally..." Zoro grinned, his hand resting on the hilt of his sword.
But nobody moved faster than Kai.
Driven by a starvation that perfectly matched his captain's, Kai's eyes locked onto the prey. Syncing his neural intent with his vocal command, he thrust his right arm forward. The Power Watch flared with a blinding, tectonic amber light.
"Elemental Power, Earth!" Kai roared.
The transformation was instantaneous. His red hoodie dissolved into geometric particles of light, instantly replaced by his heavy brown canvas jacket and tactical boots. The dense energy of the earth pulled ambient minerals from the air itself.
"Granite Broadsword!" Kai shouted.
A massive, jagged blade of solid stone materialized above the ship. He swung his arm down, directing the giant stone blade ruthlessly toward the Sea Cat's neck. "I'll butcher it first—!"
"No! Kai, stop!!!"
Princess Vivi screamed. With a vigorous, desperate stride, she launched herself off the deck, tackling Kai right at the railing just as the blade began to fall.
Kai's eyes widened. His center of gravity vanished.
Splash!
Water sprayed everywhere. Under the astonished gazes of the Straw Hat crew, the two of them tumbled headfirst into the churning sea.
The sudden shock of the cold water broke Kai's concentration. The giant granite blade disintegrated into harmless dust before it could strike the beast, and the amber light surrounding Kai shattered, returning him instantly to his soaked red hoodie.
Silence fell over the deck before the crew exploded into absolute panic.
"Vivi-chan! Don't fear, your brave knight is coming to save you!" Sanji didn't hesitate, diving into the sea with the grace of an Olympic swimmer, scooping Vivi up in an instant.
Usopp leaned over the railing, pulling at his hair. "Hey, hey, hey! Compared to Vivi who can swim, the first one to be saved should be Kai! He's a hammer when he hits the water, right?!"
"That's right! Kai can't swim!" Luffy's expression shifted from hungry to horrified. "Kai! I'm coming to save you!"
The rubber idiot grabbed the railing, fully preparing to dive in.
"Luffy, can't you have a little self-awareness as a Devil Fruit user, you idiot?!" Nami screamed, throwing Chopper directly into Luffy's path to block him.
"Honestly..." Zoro raised an eyebrow impatiently. With a heavy sigh, he unbuckled his swords and stepped up to the railing, ready to dive into the freezing depths. (I swear, I've become a professional lifeguard...)
Zoro bent his knees to jump—but stopped dead in his tracks.
"Hey guys, a little help?"
The voice came from the water. Zoro, Usopp, and Luffy peered over the railing.
Down below, treading water perfectly fine with a slightly annoyed expression on his face, was Kai. He wiped his soaked brown hair out of his eyes, paddling with smooth, practiced strokes.
Luffy's jaw literally unhinged, dropping all the way to the wooden deck with a cartoonish thud. Usopp's eyes bugged out of his skull.
"Y-YOU CAN SWIM?!" Usopp shrieked.
"Uh... yeah?" Kai replied, grabbing the rope ladder Zoro had kicked down and effortlessly hoisting himself back up onto the deck. Water dripped from his red hoodie, pooling on the planks.
"But... your powers!" Chopper gasped. "You change clothes! You control elements! You're a Devil Fruit user!"
"I never said I ate a Devil Fruit," Kai smirked, shaking the water out of his hair like a wet dog. He held up his left wrist, tapping the sleek orange face of his device. "My power comes from this. It's a Power Watch. It lets me control the elements, but it doesn't carry the curse of the sea. The water just broke my concentration so I lost my Earth form, that's all."
Luffy's eyes immediately turned into massive, sparkling stars. "SO COOOOOOL! A POWER WATCH THAT LETS YOU SWIM! YOU'RE AWESOME, KAI!"
[Aftermath on Deck]
After the chaotic revelation, the Sea Cat—which had rudely woken up from the commotion—slipped quietly away into the depths. Luffy spent the next ten minutes biting the ship's railing in pure, starvation-induced agony over the lost meat.
Kai sat cross-legged on the deck, wringing out his red hoodie. He looked up calmly at the blue-haired princess sitting across from him.
"Do you have anything to say, Vivi?" Kai asked gently.
Vivi swallowed hard. "The Sea Cat is a sacred creature of Alabasta," she said weakly. "It is a symbol of good omens. You absolutely cannot eat it..."
"Is that so? I see." Kai's face softened. He bowed his head toward Vivi, his voice utterly sincere. "It was my oversight. I apologize, Vivi."
"N-no, you don't have to do that..." Vivi flushed slightly, surprised by his earnest manners.
"Seriously, just endure it a bit longer, Luffy!" Nami rubbed her temples. She turned back to the princess. "We're already very close to Alabasta, right, Vivi?"
Princess Vivi nodded, her expression turning distant. "Sea Cats only appear in the waters near Alabasta. I estimate we'll arrive in less than half a day."
(Finally... I'm finally back. I absolutely will not let you do as you please in my country, Crocodile!) Vivi swore silently in her heart.
Sensing her anxiety, Kai gently reached out and placed a hand on the blue-haired girl's shoulder. "Don't worry, Vivi. No matter what happens, we will stand by your side."
"Yeah, we're partners!" Luffy suddenly snapped out of his depression, punching his palm. "I will definitely send that bastard Crocodile flying!"
"Alright! Anyway, once we reach our destination, the bandage on your left arm absolutely must not be removed!" Luffy commanded.
He extended his left arm forward. Immediately, the others followed suit, all wrapped securely in white bandages.
Kai looked down at his own arm. Beneath the white cloth was the black 'X'—their brilliant countermeasure against Mr. 2, and the undeniable proof of their trust. Beside it, he could feel the faint pulse of his Power Watch.
Nine arms formed a tight circle, looking exactly like a radiant sun against the blue sky.
"...This is the symbol of our fellowship!" Luffy grinned.
Kai smiled back. He wasn't a Devil Fruit user, and he wasn't originally from this world. But as the desert shores of Alabasta finally pierced the horizon, he knew exactly where he belonged.