webnovel
#ACTION
#ADVENTURE
#REINCARNATION
#SYSTEM
#OVERPOWERED
#TRANSMIGRATION
#ONEPIECE
#DEMON SLAYER

Sign-In System: One Piece, Demon Slayer & Beyond

Ron finds himself reborn in the world of One Piece, stranded on a remote island in the East Blue. But he's not just any ordinary child—he’s bonded to a mysterious sign-in system that grants him powers with every new location he visits. At his first sign-in, he unlocks the legendary Sun Breathing Technique, along with a boost to his vitality. From Shitmotsuki Village to Skypiea, Enies Lobby to Marineford, Ron travels the world, collecting extraordinary rewards that make him a force to be reckoned with. The Raikiri, one of the 21 Great Grade Swords, Armament Haki, Observation Haki, and more fall into his hands. As Ron steps onto the battlefield of Marineford during the legendary Summit War, the mightiest warriors—Four Emperors and Marine Admirals alike—pause, stunned by his presence. But Ron merely waves them off, "Don’t mind me. I’m just passing through." Join Ron on his journey across the Grand Line as he signs in at iconic locations, growing stronger with every step. This is not just an adventure—it’s a legend in the making. -------------- This is a multiverse fanfiction starting in One Piece, transitioning into Demon Slayer, then to One Punch Man, and more. If you’re only here for One Piece, feel free to stop when that arc concludes. If you love crossovers, you can continue reading :) -------------- Access 40+ chapters in advance on my Patreon: pat reon.com /ElvenKing20.

ElvenKing20 · Anime & Comics
Not enough ratings
227 Chs
#ACTION
#ADVENTURE
#REINCARNATION
#SYSTEM
#OVERPOWERED
#TRANSMIGRATION
#ONEPIECE
#DEMON SLAYER

70: Rayleigh is Shocked

"That strange feeling…"

Rayleigh narrowed his eyes, gazing intently at Ron.

What was that unsettling sensation, as if he had been completely seen through just now? It didn't feel like Observation Haki… Could it be a Devil Fruit ability?

Rayleigh didn't know that Ron possessed the power of "Transparent World," yet he still sensed a faint aura around him.

"So, this is the instinct of a top-tier fighter…"

Ron grinned. He no longer held back and unleashed his Observation Haki, along with his Transparent World ability, fully revealing their level.

A domain-like space seemed to extend from him, silently enveloping the surroundings. Every tiny detail within the area appeared in slow motion before Ron's eyes. He could see Rayleigh's movements clearly, down to the blood flow within his body, the beat of his heart, and the subtle shifts of his muscles.

"This strange sensation again… So, it's really a Devil Fruit ability?" Rayleigh squinted, instinctively feeling as though he were being watched.

Watching Ron from a distance, Rayleigh closed his eyes and fully unleashed his own advanced Observation Haki.

"Are you there…"

A smirk formed on Rayleigh's lips. He shifted his stance just as Ron launched an attack from above. Ron's foot smashed down, narrowly missing as the ground shook beneath them. The area collapsed in a wide radius, sending debris scattering.

Amidst the smoke and dust in the massive crater, the two figures moved at high speed, flashing in and out of sight. One tried to land a hit, but the other evaded, leaving the attack to strike empty ground repeatedly.

The earth trembled as the crater grew deeper and wider, unable to withstand the relentless barrage of strikes. When Ron's last strike missed, Rayleigh's voice rang out beside him.

"Is that all you've got, kid?"

Ron's eyes narrowed as details from his Transparent World Sight flooded his mind. Without hesitation, he swung his fist to the side. But Rayleigh was a step ahead, having anticipated Ron's move with his advanced Observation Haki. He countered at lightning speed, kicking Ron from below in the abdomen, sending him flying upward.

Ron choked, coughing up a mouthful of spit, before plummeting down like a meteor, crashing into the ground.

Rayleigh lowered his leg, his eyes filled with curiosity and surprise as he watched the boy stand up, brushing off the dust as if it were nothing. A young man like him, with such strength, possessing both Armament and Observation Haki at this level? Rayleigh couldn't understand it. This boy's physique and talent were beyond anything he'd ever seen, not even comparable to the famed "natural monster" Big Mom at this age.

Could this kid be a similar natural anomaly?

Ron took a deep breath as he stood, then dashed forward, skimming along the ground, rapidly closing the distance between himself and Rayleigh. He aimed a punch at Rayleigh's face, but stopped just short, the force of his blow stirring Rayleigh's silver hair back.

"Not fighting anymore?" Ron asked, frowning.

"Nope," Rayleigh replied, eyeing Ron's dust-covered, tattered clothes. "I'm not as lively as you youngsters."

Rayleigh turned and headed toward the edge of the crater. Though Ron wasn't fully satisfied, he let it go since Rayleigh had no intention of continuing. He dispersed his Armament Haki, following Rayleigh out of the crater.

While retrieving their outer jackets that had blown away in the chaos, Ron asked, "Mr. Rayleigh, how much of your strength were you using against me? Was it even 10 percent?"

He could sense that Rayleigh's power, both physically and in Haki, was more than double his own. Even though he hadn't yet used his sword skills, he suspected that Rayleigh's swordsmanship might surpass his own.

Rayleigh's eyebrow twitched. "Ten percent? Kid, are you overestimating me, or underestimating yourself?"

Rayleigh didn't realize Ron's uncertainty about his own strength was why he had sought this challenge. Back at Marineford, he had seen Garp only a handful of times, but they had never sparred. Even other officers avoided engaging him. Only Hina had sparred with him a few times, though she was still too weak to hold his interest.

The only meaningful match he'd ever had was against Gion, which had been an unusual encounter...

Rayleigh found his white coat, bent down to pick it up, and asked, "Kid, who taught you Haki?"

"Garp," Ron replied honestly.

Rayleigh's eyes narrowed. "So you're Garp's disciple?"

"No, he just taught me the basics of Armament Haki as part of an agreement," Ron replied.

Rayleigh nodded, not pressing the matter further.

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