Strongest Sign in system throughout the multiverse

Roy Jenkins was your average 21-year-old college student. With his nose buried in manga and anime, he had a particular obsession with One Piece. He often dreamed of what it would be like to sail the Grand Line, searching for treasure and facing powerful foes. But dreams were dreams. Or so he thought.

On a typical night, Roy was lounging in his room, rewatching the One Piece Marineford arc for the umpteenth time. The intensity of Whitebeard's final stand gave him chills every time. Suddenly, his screen flickered, and everything went black.

"What the—?" Roy barely had time to react. A swirling vortex opened behind him, pulling him in. Everything around him blurred into a kaleidoscope of colors before fading to black.

When Roy opened his eyes, he found himself lying on a sandy beach. The sound of waves crashing and seagulls cawing filled the air. The sky was impossibly blue, and the salty breeze was undeniably real. He sat up, heart racing.

"No way… This isn't Earth, is it?" he muttered.

A soft chime echoed in his head, startling him.

"Welcome to the One Piece world, Roy. You are now bound to the Sign-In System. By signing in at important locations, you will receive rewards that will make you one of the strongest in this world. Good luck!"

Roy blinked as a translucent screen appeared before him:

Location: Shells Town

Sign-In Available

Do you wish to sign in?

"Shells Town? Isn't this where Zoro is?" Roy's pulse quickened. He knew this was the start of Luffy's journey to form his crew. If he played his cards right, he could meet Zoro and maybe even Luffy. But first, he had to figure out what this Sign-In System was all about.

"I'll take my chances. Yes, sign in!" he said aloud.

The screen shimmered before a booming voice filled his ears.

"Congratulations! You have signed in at Shells Town and earned your first reward: the Supreme Swordsmanship Skill! Additionally, you receive the rare-grade blade, Kurogane, and a beginner's Armament Haki mastery!"

Roy's body tingled as knowledge of swordsmanship flooded his mind. Techniques, stances, and strategies that would take years to master were now second nature. A sleek black katana materialized in his hand. It was light but radiated a menacing aura.

"Holy crap. This… this is insane!" Roy whispered, staring at the blade.

Gathering his thoughts, Roy decided to explore the town. He quickly realized he was near the naval base where Helmeppo was terrorizing Zoro. He spotted Zoro tied to a post in the courtyard, his iconic green hair unmistakable.

"Zoro," Roy muttered, heart pounding. He'd just arrived in this world, and here was one of his favorite characters right in front of him.

A commotion broke out as Helmeppo strutted into the courtyard, taunting Zoro with his smug grin.

"I can't just stand here," Roy thought. He tightened his grip on Kurogane and stepped forward.

"Hey, you! Blondie!" Roy called out, his voice steady.

Helmeppo turned, his sneer replaced with confusion. "Who the hell are you?"

Roy smirked, confidence brimming thanks to his new skills. "Just someone who doesn't like bullies."

Helmeppo's face turned red. "You dare insult me? Guards! Arrest him!"

Two marine soldiers lunged at Roy, swords drawn. Without thinking, Roy moved. His body reacted as if he'd been training for years. He sidestepped the first soldier, disarmed him with a swift motion, and struck the second with the hilt of his blade. Both collapsed, groaning in pain.

Zoro's eyes widened slightly. "Who's this guy?"

Helmeppo backed away, trembling. "You… You'll regret this! My father is the captain of this base!"

Roy ignored the brat and turned to Zoro. "You want to get out of here? I could use a swordsman like you."

Zoro raised an eyebrow. "What's in it for me?"

"Freedom," Roy replied, holding up Kurogane. "And a chance to fight someone who's already mastered swordsmanship."

Zoro smirked. "Interesting. Alright, let's see if you're as good as you think."

And just like that, Roy's adventure in the One Piece world began. With his Sign-In System and newfound abilities, he was ready to carve his path and challenge the mightiest of foes. The Grand Line awaited.