"Then I'm coming!" Kaido raised his massive iron mace, his tone half eager, half uncertain.
"Come on," Kaoru Tsubasa replied calmly.
Kaido gritted his teeth. At worst, he'd just hurt the guy and owe him a lifetime of apologies. He swung the weapon down with all his strength—
Boom!
A thunderous crash echoed across the deck. The impact sent shockwaves rippling outward, but Kaoru's right hand remained completely unscathed—while Kaido himself was blasted backward, tumbling across the floor.
The sound drew the attention of nearby crew members.
"Why's the new guy fighting Kaoru?"
"Does that brat think he can take him on?"
"Ridiculous. Kaoru Tsubasa fought on par with Lord Shiki himself! A rookie like that doesn't stand a chance!"
When the Golden Lion Shiki overheard the comments, his eyelid twitched. He almost wanted to fly over, grab the nearest idiot by the collar, and yell: I was just holding back, you fools! But saying that would sound childish, so he turned away, pretending not to care.
Kaido staggered to his feet, shaking his numb hands."So hard..." he muttered.
Kaoru smirked. "Now you understand the purpose of Armament Haki, right? It reinforces your body and can even coat your weapon to enhance its attack power."
"That's awesome! Brother Kaoru, can you teach me?" Kaido asked, his eyes burning with excitement.
"Brother?!" Kaoru blinked, slightly amused. Did the future Beast King just call me that?
He nodded. "Fine. I'll teach you Armament Haki."
In truth, he'd been about to refuse—but the system's voice chimed in.
[Ding — Mission triggered: Train Kaido to master all three types of Haki. Reward: 200 Sword Skill Points and 200 Spirit Points per mastery.]
A total of six hundred points—what normally took months of effort. Kaoru's grin widened."Alright then. Let's begin."
Kaido beamed. "Yosh!"
"Tch, the kid doesn't even have Haki yet," Shiki muttered. "Why'd the captain even bring him aboard?"
"Gurararara! Everyone starts somewhere," Newgate—Whitebeard—laughed, taking a swig from his sake bottle.
Over the following days, Kaoru patiently trained Kaido in the basics of Haki. To his surprise, Kaido's talent was terrifying. Within just three days, the boy managed to grasp the fundamentals of Armament Haki—his arm not yet fully coated, but close.
"Captain! A pirate ship spotted ahead!" shouted a lookout.
"Wahahahaha! Fire the cannons, men! Leave no survivors!" Rocks roared.
The Rocks Pirates surged into battle. Yet the top members—Shiki, Newgate, Big Mom—barely glanced their way. To them, these were just small fry, not worth unsheathing a blade for.
"It seems there's someone decent aboard that ship," Kaoru muttered, focusing his Observation Haki. "Kaido, want to test what you've learned?"
He sensed a presence—roughly equal to Kaido's current strength. Perfect for a spar.
"Alright! Let them witness my progress!" Kaido shouted, leaping across the waves to the enemy vessel.
Kaoru sighed and followed. Knowing Kaido's impulsive nature, leaving him unsupervised was asking for trouble.
When they landed on the opposing deck, a tall man with a sheathed katana stepped forward.
"My name is Yanxide Mitsuya, captain of the Sword Pirates," he introduced with a bow.
"Whoever you are, take my blow!" Kaido yelled, charging in with reckless enthusiasm.
The swordsman dodged effortlessly, springing back as Kaido's mace smashed into the deck, splintering the wood.
"Ittoryu: Quick Draw!"
A flash of light cut through the air. Kaido staggered backward, a thin wound across his chest.
Kaoru narrowed his eyes. As expected. Speed's still Kaido's biggest flaw. Without refined Observation Haki, he couldn't predict attacks yet.
"Gah! You're not getting away!" Kaido lunged again, swinging wildly. His attacks were raw power—each blow enough to crack a hull—but Mitsuya evaded them all with surgical precision.
The swordsman's eyes hardened. There's another fighter watching… I can't retreat. I'll have to go all out.
"You dare to space out mid-battle?!" Kaido roared and brought his weapon down with all his might.
The impact didn't land on Mitsuya, but it did split the entire pirate ship in half.
The watching Rocks crew whistled in disbelief. Even seasoned warriors couldn't cleave a ship barehanded.
"Ittoryu: Tiger Leap!"
Mitsuya's slash forced Kaido back several meters, buying him distance. His expression turned solemn."I know I can't escape… but before I die, allow me to unleash the sword I've honed my entire life!"
Violet mist began to rise from his body, condensing into the blade in his hand.
"The life energy of a swordsman," Shiki muttered from afar, recognizing it instantly.
"Ittoryu Secret Technique—Sword Body!"
A devastating arc of energy roared toward Kaido. His instincts screamed death. Too fast to dodge, too powerful to block. He braced himself—mace across his chest—hoping to survive.
"Spirit Art — Defense: Photon Shield!"
Kaoru's voice cut through the chaos. Three glowing barriers of light formed between Kaido and the incoming slash.
Crack! Crack! Crack!
All three shattered in an instant. The attack still landed—but the power was halved.
Kaoru's plan had worked.
Boom!
Kaido's mace exploded into fragments. The impact hurled him overboard into the sea.
"Spirit Art — Wind Assist!"
Kaoru's spell summoned a swirling gust, lifting Kaido from the water and setting him gently back on deck. A deep sword scar ran diagonally across his chest—but he was still alive.
So that's the man who'll one day be the strongest creature alive, Kaoru thought in awe. Even half-dead, he refuses to break.
Mitsuya, however, staggered back—his body aging rapidly."My strongest strike… and he still lives? I lose," he whispered.
His flesh turned to ash, leaving only bones, a blade, and a Devil Fruit.
Kaoru knelt and picked them up.
[Ding — Devil Fruit detected: Zoan-type, Fish-Fish Fruit, Mythical Beast — Azure Dragon form.][Triggering selection mission…][Option 1: Absorb the Devil Fruit and alter the One Piece timeline. Reward: 300 Sword Skill Points, 300 Spirit Points.][Option 2: Give the Devil Fruit to Kaido, preserving the timeline. Reward: 300 Sword Skill Points, 300 Spirit Points, and unlock the Lottery Store.]
"I'll take the second option," Kaoru said without hesitation.
[Reward granted: 300 Sword Skill Points, 300 Spirit Points.][Lottery Store unlocked.][Warning: If the host consumes the Devil Fruit instead, all current powers will be revoked.]
Kaoru smiled faintly. "Don't worry. I'll stick to my choice."
Using his spiritual energy, he lifted Kaido's unconscious body and returned to the Rocks ship. He laid the future Emperor gently on his own bed and bandaged the wound himself.
Kaido was still just a regular crewmate, and the lower decks were cramped—dozens of men sharing a single room. But Kaoru had earned a private cabin long ago.
He glanced at Kaido's sleeping face and muttered,"Rest up, little brother. The sea's going to remember your name one day."