Before embarking on this journey into the Void Century, it's essential to understand the unique mechanics that govern this story. The world you know from the main timeline—the rampant Devil Fruits, the power of Haki, and the political landscape—has yet to fully form. This is a time of nascent power and ideological conflict, where the rules are still being written, and our protagonist, Kuro, is one of the authors.
The Power System: A World in Flux
In this era, Devil Fruits are not as common or as well-understood. They are more akin to rare, mythical artifacts, often found and fought over by the great powers of the time. The concept of curses, the inability to swim after eating one, is non-existent. The Sea is not an enemy to be feared; it is simply a vast, unpredictable expanse. Similarly, Haki is a fledgling power. Only a select few, like our drunken master Roger, have begun to grasp its nuances, and even for them, it is a demanding discipline, not an everyday tool. This story focuses on the raw, unrefined nature of these abilities, and how they evolve and are refined by the trials of a brewing war.
Kuro's Powers: The Strategist's Gambit
Kuro's abilities are twofold, a duality that reflects his very nature. His primary power comes from the Yami Yami no Mi, the Dark-Dark Fruit. Unlike the version you may know, this Yami Yami no Mi is not a cursed Logia. Instead, it is a power of pure, unadulterated darkness and absorption. He cannot turn into darkness to evade attacks, but he can create and manipulate shadows, absorbing light and objects into a bottomless void. This makes him a master of stealth, a purveyor of secrets, and a prankster who can make an entire feast disappear in a blink. His strength lies not in direct combat but in a more subtle, strategic application—stealing intel from a noble's safe, trapping an enemy agent in a fleeting moment of pure shadow, or creating diversions that allow his crew to escape impossible odds.
His secondary, and arguably more critical, power is the Oath-Keeper's Geas System. This is the core engine of the narrative. It is not a classic "cheat" system that provides easy answers or immense power. Instead, it operates on a simple, yet profound, rule: Kuro must forge and fulfill unbreakable vows. The System's very existence is a secret, a mental voice that guides him, sometimes with cryptic advice, sometimes with a clear warning. Every vow he makes—an alliance with a new kingdom, a promise to protect an innocent, a gamble with a rival—is logged and tracked. The System levels up not through combat or experience points, but through the sheer number of vows he makes and keeps.
These vows are double-edged swords. A "Blank Vow" can be used as a strategic tool to steal a rival's attribute (like Intellect or Charisma) in a high-stakes gamble, but a failed vow can result in the loss of one of his own stats. The System is a tool of consequence. It forces Kuro to be a man of his word, to consider every action and its ripple effects, because a broken vow has a severe price. This mechanic ties directly into the tragic nature of the story—the more Kuro promises, the more he risks, and the more he is bound to a predetermined fate that may lead to the very war he's trying to prevent. It is a system that demands integrity and strategy, not mindless power, and it will be the lens through which he views his grand, and ultimately heartbreaking, adventure.
Chapter 1: The Oath-Keeper's Gambit
The air was thick with the scent of wet earth and ancient decay. It clung to the back of Kuro's throat, a grim, humid welcome to a reality he hadn't chosen. He lay on a bed of damp moss, the chill seeping through the thin, unfamiliar tunic he wore, a cheap, scratchy fabric that felt nothing like the tailored clothes of his old life. He opened his eyes, but it did little good. The darkness was absolute, a suffocating blanket woven from a lack of light and a strange, heavy absence of sound.
He lifted a hand, a pale, almost ethereal thing in the void, and for a panicked moment, he couldn't feel it at all. It was only when a cool, slick sensation ran across his palm that he realized his own shadow had coalesced and was twisting around his fingers, a silent, living thing. A nervous, half-hysterical laugh bubbled up from his chest, a sound that felt out of place and wrong.
"So… this is my new life? A cave and a disembodied voice in my head? Seriously?"
This is a fever dream. A really, really bad one. A prank from the universe, and I'm the punchline.
A cold, precise whisper echoed in his mind, sharp as glass.
[SYSTEM: PROGRESSION - VOW COUNT: 0. OBJECTIVE: FORM CREW.]
The message hung there for a moment, a sterile pronouncement in a world of damp, living things. He sat up, his back cracking with a protest that felt far too old for him. He reached out with a purpose, trying to draw in a little of the darkness for a simple, controlled action. The shadows on the wall, already dancing in the faint light that seeped through a crack in the cave's roof, seemed to writhe and stretch toward him. The small, innocuous blob he'd been aiming for swelled into a monstrous, spiny creature with far too many eyes. It shrieked, a soundless scream that was more of a feeling—the feeling of a cold wind against his skin—before it dissolved into nothingness. Kuro yelped, an undignified sound that bounced off the cavern walls. He ran a hand through his hair, a useless gesture in the dark.
Okay, that was not ideal. Note to self: The joy is in the control, not the chaos.
[SYSTEM: TUTORIAL – YAMI YAMI NO MI ABILITIES ARE TIED TO HOST'S EMOTIONAL STATE. CONTROL THE JOY, CONTROL THE SHADOW.]
He closed his eyes, focusing on a single, focused feeling: quiet confidence. The cool logic he used to apply to complex programming problems in his past life. He reached out with his mind, and this time, a small, dark orb formed in the center of the cavern, a perfect sphere of nothingness. He made it twist into a cat, then a bird, then a tiny, swirling tornado. A faint, almost imperceptible shadow in the corner of his eye shifted and disappeared as soon as he focused on it. He squinted, but it was gone.
[SYSTEM: INSIGHT – THE 'GOLDEN PHOENIX' IS HELD CAPTIVE NEARBY. LOCATION: NOBLE'S GARRISON. THREAT LEVEL: LOW.]
A clue. A single thread in this mess. He grinned. This was a game. A game he could win. The shadows on the wall seemed to grin with him, mirroring his mischievous expression. He would use them, not for confrontation, but for deception. He would find a way. The shadows seemed to vibrate with a new purpose, and he felt a thrill, cold and delicious, run down his spine. His next move was clear. He was going to set a drunkard free.
The noble's fortress was a monstrosity of white stone, jutting out of the cliffside like a rotten tooth. The air, still and humid, was now filled with the cloying scent of stale wine and roasted meat. Kuro merged with the long, dark shadow of a guard tower, his body becoming a part of the inky blackness. He could feel the cool stone beneath him, the texture of the moss in the cracks, the vibrations of footsteps on the path above. He flowed through the complex, a silent, invisible stream, passing guards too preoccupied with their nightly rounds to notice the creeping darkness beneath their feet. He saw a few of them huddled together, sharing a bottle, their laughter echoing in the night. Their sloppy carelessness made his task all the easier.
He found him in a holding cell, not a dungeon. The guards must have figured the man was more of a nuisance than a real threat, a loud, drunken pest. Roger was leaning against the bars, a half-empty wineskin in one hand, shouting at a bored-looking guard.
"Oi! The sun's too bright in this cage! Tell 'em to turn it off, would ya?"
The guard just sighed and shook his head, looking more tired than annoyed. Roger seemed to feed off the man's exhaustion, his grin widening.
"They said I was a menace! A criminal! They put me in a cage with a view of the sea! What a joke! My name is Gol D. Roger! The Pirate King! And this… this is just a vacation! Ahahaha!"
His laugh was a boisterous, rolling thing that echoed down the stone corridor. Kuro watched him from the shadows of a nearby pillar. The man was a hurricane, a force of nature crammed into a tiny cell. A flash of a golden, almost ethereal light pulsed on his chest for a moment before fading. The Phoenix Fruit. Kuro had to be careful. He could see the deep sadness beneath the drunken bravado, the glint of tears in his eyes when he thought no one was looking.
He's not a prisoner. He's a showman who's lost his stage. I'm not here to free him. I'm here to give him a new show.
Kuro stepped out of the shadows, becoming a solid figure once more. The guard, startled, reached for his sword.
"Hey! Who're you? This is a restricted area!"
Kuro raised his hands in a placating gesture.
"Relax, friend. I'm just a humble merchant, looking for a way to get out of this town. And I think… I think this man can help me."
He pointed at Roger. The guard's brow furrowed. Kuro knelt, pulling a small, carved wooden box from his tunic.
"This is a rare treasure, a relic from the past. I'll give you this, and all you have to do is make a simple vow. A vow to… forget this cell. To forget the man in it. To just walk away and get a nice, long rest."
The guard's eyes went wide. He looked from the box, to Roger, to the box again. The lure of the vow was too strong.
"You… you're not a trick, are you?"
"Let's just say I'm here to offer you a better drinking spot. Vow?"
The man, with a shaky hand, touched the box.
[SYSTEM: VOW ACTIVATED – 'FORGET THE PHOENIX'S CELL.' VOW TAKER: NOBLE GUARD. VOW STATUS: SUCCESS.]
A wave of confusion washed over the guard's face. He blinked, looked around, and shook his head.
"Weird… I could've sworn… eh, must be tired."
He turned on his heel and walked away, not bothering to look back. Roger, who had been watching the whole thing with a look of drunken wonder, stumbled over a sleeping guard who was curled up in the corner. He flapped his arms in a half-hearted attempt to fly before sprawling on the ground with a soft thud. He let out a loud snort.
"Ha! This cage isn't even locked! What a joke!"
He pushed on the bars, which, thanks to the guard's forgotten duty, swung open with a rusty creak. He staggered out, grinning at Kuro.
"You're a clever one, aren't ya? I like you!"
He clapped Kuro on the back, the force of it almost knocking him over.
"I knew I wasn't dreaming! This world is a lot more fun than I thought it was going to be! Cursed by the sea, my ass! This is just a new beginning!"
The irony of him talking about Haki and a "cursed" world is not lost on me. He's a paradox. A drunken, charismatic, brilliant, broken paradox. And I'm in charge of his narrative now.
The path was now clear. A new adventure, with a new ally, lay just outside the fortress walls.
The docks were quiet, save for the rhythmic sloshing of water against wood. The mist, thick and clinging, made the lanterns on the ship masts glow with a soft, ethereal light. The air was cool and salty, a sharp contrast to the dank air of the cave and the stale atmosphere of the prison. The Aurora Sovereign sat at anchor, a thing of impossible beauty. Its hull was a brilliant, shimmering gold, a stark contrast to the utilitarian ships around it. It looked less like a vessel and more like a king's carriage waiting to take its monarch home.
Roger, his drunken stupor replaced by a quiet, thoughtful calm, ran a hand along the ship's railing.
[SYSTEM: LORE INSIGHT – THE AURORA SOVEREIGN'S HULL IS COMPRISED OF 'ORICHALCUM,' A SELF-REPAIRING METAL. IT REPAIRS MINOR DAMAGE OVER TIME, AND MAJOR DAMAGE WITH FOCUSED ENERGY.]
Roger let out a low whistle.
"She's a beauty, isn't she? My boy, I knew you had good taste."
He turned to Kuro, a serious glint in his eyes.
"So, you're telling me a magic voice in your head wants us to make promises? Sounds like a good time to me!"
Kuro smirked, leaning against the railing.
"Yeah, something like that. Just be careful what you say around me, alright? This 'System' as it calls itself… it takes vows seriously."
He paused, choosing his words carefully.
"It's like a contract. An unbreakable one."
Roger laughed, a genuine, booming sound that made the seagulls on a nearby mast take flight.
"Hah! A contract with a drunk and a shadow-man? I like it! So, what's the first promise?"
Kuro didn't hesitate. He had been planning this since the System mentioned the "Golden Phoenix."
"A vow to find a worthy crew. One that can stand by your side, not just as followers, but as partners."
The words were a quiet, powerful thing in the misty air. Roger's smile faltered for a second, a fleeting moment of vulnerability before it returned, even wider than before.
"A crew… yeah, I like that. We'll find the strongest, the funniest, the kindest people in the world! We'll show this world what a real crew looks like!"
He held out a hand, a gesture of pure, unadulterated trust.
"I, Gol D. Roger, vow to find a worthy crew."
[SYSTEM: VOW ACTIVATED – 'TO FIND A WORTHY CREW.' VOW TAKER: GOL D. ROGER. VOW STATUS: ACTIVE.]
The first vow. The first step on a journey that will change the world. This isn't just a game anymore. It's real. The weight of my past life feels a little lighter now.
They stood there for a long time, watching the sun begin to peek over the horizon, painting the sky in a wash of soft pink and orange. They were no longer two lone wanderers. They were a crew. And with a single glance, a silent, shared understanding, they turned and boarded the Aurora Sovereign. Their first voyage began not with a bang, but with the soft, gentle push of the tide, carrying them toward a new horizon and a new goal. Their first mission was to find their next member, someone who could bring a different kind of strength to their fledgling crew.