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One Piece: With Sign-in System

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 unimaginable power 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.

ElvenKing20 · Anime & Comics
Not enough ratings
26 Chs

Growing Stronger Together: Days in the Dojo

With a loud thud, Kuina's bamboo sword dropped to the ground. She stared blankly at the black-haired boy sitting in the snow, his upper body bare, muscles slightly flexed, yet with incredibly defined lines.

At this moment, Kuina somewhat understood why, even though Ron looked younger than her, his strength was so overwhelming.

Ron, on the other hand, looked at Kuina, his face full of confusion.

"Did you need something from me?"

Kuina snapped back to reality, remembering her purpose, and quickly bent down to pick up two bamboo swords. With a firm gaze, she said to Ron, "I'm here to challenge you."

Ron scratched his head. "Didn't we fight yesterday?"

"That was because I was careless. Today, I'll show my real strength."

"Oh, alright then."

A moment later, Kuina's bamboo sword was sent flying.

She looked at her trembling hands, gritted her teeth hard, and stared at Ron, saying, "Tomorrow, I'll come again!"

"I'm always ready," Ron replied with a smile, shouldering his bamboo sword.

Kuina shot him a fierce look and turned to leave.

She had only taken a few steps when Ron's voice echoed behind her.

"Your speed is decent, but your strength is lacking. At this rate, you won't be able to defeat me."

Kuina stopped in her tracks, her fists clenching slightly, biting her lower lip.

The weakness in strength was her sore spot. She had cursed countless times that she was born a girl, as women's strength was naturally weaker than men's. And this difference only became more pronounced as time went on!

That's why her father, Koushirou, bluntly told her that as a woman, she would never become the world's greatest swordsman.

"I know! I know my weakness is my lack of strength!" Kuina shouted, her back still turned to Ron.

"No matter how hard I train, my strength can't match that of you boys!"

"If I could, I would want to be a boy too!"

Her voice was full of frustration.

Ron paused for a moment, then understood.

"It seems you've misunderstood me. I'm not mocking you. I was asking if you'd like me to teach you a method to increase your strength."

Kuina's body trembled.

"A way to increase strength?"

She turned her head toward Ron.

"Can you really help me improve my strength?"

Ron nodded. "I think so."

Later in the day, in the forest behind the dojo.

Ron handed Kuina a grilled fish.

"Eat this."

"Will eating it increase my strength?" Kuina asked with suspicion.

"It's part of the process."

Kuina quickly devoured the grilled fish, surprised by how delicious it tasted.

"Full?" Ron asked, watching her.

Kuina nodded.

"Good," said Ron, then began guiding her.

"Now close your eyes and do exactly as I say."

Kuina followed his instructions and closed her eyes.

"From now on, you need to adjust your breathing to my rhythm," Ron's voice echoed in her ears.

"Take a deep breath and completely exhale all the air from your lungs..."

What Ron was teaching Kuina now was a simplified version of the Sun Breathing Technique. He had discovered that after eating a full meal and using the breathing method, one could quickly absorb the energy from food. While it didn't directly increase vitality, it was highly effective in boosting strength.

"How do you feel?" Ron asked.

Kuina slowly opened her eyes. The feeling of fullness in her stomach had disappeared, replaced by a sense of hunger. She clenched her fists.

It seemed like... she had indeed gained some strength.

A flicker of excitement flashed in her eyes. But to make sure it wasn't just a feeling, she suddenly stood up and ran off, saying, "I'll go test it out!"

"Hey," Ron called after her, watching as she disappeared into the distance. He shook his head and smiled.

A while later, Kuina returned, looking disappointed.

"It seems like it was just an illusion. I still can't lift that stone weight with one hand..."

Ron, still swinging his bamboo sword, said, "Gaining strength isn't that fast. Try again in ten days."

For the next few days, it seemed Kuina was spurred on by Ron. When Ron arrived at the training ground at 4 a.m., Kuina was already there, holding her bamboo sword.

The two would spar first, and then they would each focus on their own training, not bothering one another.

After the sun rose and they ate breakfast at the dojo, they would both practice swordsmanship under Koushirou's guidance. This included footwork, body positioning, gripping the sword, drawing the sword, and various strikes.

In the afternoon, Ron and Koushirou would spar with real swords, while Kuina watched. The more she watched, the more pressured she felt, and she would often leave after a short while to practice on her own.

In the winter, the dojo felt especially quiet. The children who came to learn swordsmanship stayed home because of the cold, reluctant to visit the dojo. Occasionally, some familiar villagers would stop by for a chat. Usually, it was just Koushirou, Kuina, and now Ron.

It wouldn't be until spring when the place would become lively again.