Monster of the Grand Line

Disclaimer: This story is for adult only! Read it at your own arousal!

– Story Start –

"So, what's the goal, Naruto?" asked the small orange fox, curiously. The small creature was sitting on top of a desk, which plastered with documents and notifications. Nine tails curled around its body. It was looking up at the blond-haired young man with deep oceanic blue eyes.

Naruto yawned while rubbing his temple with two fingers. His mind absorbed the new memory. He hated it whenever that happened, but there wasn't anything he could do about it. Once the painful migraine died down, he looked at the full body mirror to the side wall and took a moment to scrutinize his adult appearance.

"How long has it been since…" Naruto muttered and reminisced about the Elemental Nations. He had been away from his home for a long time, a very long time. He shook his head and turned his attention back to his partner and friend. If it wasn't for the fox accompanying him on his journey, he would have gone insane a long time ago – or worse.

"I have no idea, Kurama," Naruto answered calmly with a smile. "There's no introduction window this time, and I can't open the quest window either."

"Sandbox mode then?" Kurama pointed out thoughtfully. This had happened before. "I don't mind if that is the case."

"Does that mean I can do whatever I want?" Naruto asked. His lips curved into a devilish grin. His mind raced as he thought of all the things he could do with the freedom comes with sandbox mode. And to make it even sweeter, the curse mark plastered on his neck was inactive, meaning all of his powers is unrestricted in this world.

"Yes probably, but first thing first," Kurama pointed out and flexed its nine tails. This was a new world with new rules governing it. They must prepare themselves for when things inevitably go south. "I was inserted and judging from where we are and what you're wearing, you're displaced."

"Yeah, I was displaced," Naruto nodded and recollected his memory.

Naruto had displaced a person named Momonga the moment he transited into this world. That person held the rank vice-admiral in the Marine, which is part of the World Government. It took a moment to recollect himself after the sudden transition since a lifetime of a person was taxing regardless of his mental fortitude.

"I already know that," Kurama said, a bit annoyed. It hated being left in the dark, and currently, it had no knowledge or information on the world they were currently resided in. "Where are we?"

"We're at in the place called Calm Belt…" Naruto began.

It took a couple of hours to explain everything Naruto had learned since his transition into this world to Kurama. The fox – once feared as the strongest chakra beast – paid undivided attention throughout the explanation.

"Interesting setup for a world full of oceans," Kurama said simply once it fully understood the state of things from Naruto. It had accompanied the blond to a lot of whacky worlds, and this one wasn't the wackiest. "I liked to explore the world for myself, but I'm more curious about where we stand in term of power level. I don't mind a good fight, but I don't want to be in for a major surprise, especially from these devil fruit users."

"Me either," Naruto said and shivered. He was powerful Shinobi, but that was back when he was still in the Elemental Nation. He didn't know how he compared to this new world until he fought with his all against one of the strongest people available. "I wouldn't want to fight logia-type devil fruit users if I can help it, but I'm sure the asshole going to put me into that situation for laughs and kicks."

Kurama nodded, knowing exactly who Naruto was referring to. "Well, at least the devil fruit users have a weakness we can exploit, and Armament Haki will allow you to deal actual damage to their real body regardless of their intangible ability. How good are you at it?"

"At Armament Haki? Well, Momonga is a Vice-Admiral in the Marine. I have all of his trainings and battle experiences, so I guess I'm fairly good at it," Naruto said and focused his chakra, "but I think can do better, probably."

Dozens of shadow clones popped into existence around the cabin. The shadow clones began fighting each other, evading each other with near perfection thanked to Observation Haki. Some managed to get a few hits in at first because Naruto wasn't used to his new sensing ability, but more shadow clones summoned to the ones that were dispelled. With his near bottomless chakra, Naruto could keep this cheating training up indefinitely.

"Vice-admiral! Vice-admiral!" the door to the cabin suddenly opened. Entered one of the marines, his subordinate. Naruto had a few hundreds of men under his command as his ship was sailing through Calm Belt. He felt a sense of comradery amongst his men, so their relationship with their former vice-admiral was very good.

"We are at the rendezvous point…"

The marine blinked at the numerous vice-admirals fighting each other around the room. He had never seen anything like that before. Was that a devil fruit? As far as he recalled, the vice-admiral didn't have any devil fruit power. "What…?"

"Already? Tell the men to get stand ready, it might take a while for the other party to show up," Naruto interjected and dismissed the clones with a thought. He didn't want to explain his otherworldly power and let his men believed whatever they would come up with. He was about to dismiss the marine, but he wanted to make sure something else. "By the way, what's my name?"

"Vice-admiral?"

Naruto winced. "I'm asking for my name, not my rank."

"Vice-admiral Naruto Uzumaki?" the marine said, puzzling. "What was that, sir? Was that a devil fruit power?"

Naruto nodded with approval. It seems the power-that-be had allowed him to keep his body and name for the sake of simplicity. It was always annoying when people in whatever world he was deposited on called him by a totally unfamiliar name, especially when he was banging a g– trying to accomplish a mission.

"That is nothing for you have to worry about," Naruto said. "You can go now but stay vigilant since we are in the Calm Belt where a lot of dangerous Sea Kings live. We are also expecting one of the Warlords so don't let your guard down."

"Yes sir," the marine saluted and left the room. Everyone in the Grand Line knew the danger of the Calm Belt and sitting in one spot for too long in the Calm Belt wasn't a good idea.

"We are expecting a warlord?" Kurama asked. It noticed that the marine didn't pay any attention to it, which was a very good thing. That mean while the fox was inserted into the world with Naruto, it was not an abnormality, so it didn't need to hide or explain itself to anyone.

"Apparently," Naruto said and recalled the recent memory. "I'm currently under order from the World Government to retrieve a Warlord named Boa Hancock and take her to the compulsory summoning or something like that. We're preparing for war or some sort. Seems like the higher up caught a highly dangerous individual named Ace, son of some King of Pirates, and they want to make an example of him."

"Kind of extreme don't you think? Punishing a child for the sin of their father, but war huh?" Kurama grinned. "Your underling wasn't surprised by my presence, so I assumed that even if I'm inserted, the marine is fully aware of who I am. With sandbox mode, maybe I can go all out in this place and not have to worry about killing important characters."

"Sure, whatever," Naruto said as dozens shadow clones reappeared in the room. They began attacking each other using Observation Haki as well as Armament Haki. He thought about who he was going to escort by order of the World Government, and it must because the power-that-be wished him to do so. They wanted him to seduce and mate with Boa Hancock – that much was obvious.

"We're going to be here a while," Naruto said and leaned back against his chair. "So I'm going to train to pass the time. It's good that I don't have to learn the basic since Momonga already knew them."

Kurama nodded and watched the battle royal in the sizable cabin, but when one of the cloned used a compressed air blade and destroyed one of the walls, causing the marines outside to stare in shock, it sighed. Another air blade flew across the room, bisecting a handful of clones before the entire wall of the cabin. "Maybe we should find somewhere more spacious to train."

"Vice-admiral!" the marine called out as the cabin collapsed into itself as a couple of more air blades erupted. Tears were streaming down their faces. "Please don't damage the ship!"

"Hahaha, sorry, sorry," Naruto apologized and climbed out of the rubbles with Kurama sitting on top of his head. All the shadow clones had been dispelled when the cabin collapsed. "I'm going out to train for a bit, and umm… fix that up before I get back."

"But what about the Warlord summoning?" the marine asked while a lot of them was yelling about why they must fix a cabin he destroyed for no good reason.

"She won't be here for a while – or a long time, and I will probably be back before she gets here. See you all in a couple of weeks. Don't get yourself killed now," Naruto said and drew a seal onto the deck of the ship. It was a Hiraishin seal for easier return. He then jumped off the side of the ship, causing all the marines to yell his name in shock and rush to the side and look for him.

"How does the Vice-admiral do that?" many of them thought as they stared wide eyes towards their commander. He was running on top of the water, into the distant. It didn't take more than a minute for him to vanish from view. "Did the vice-admiral said he will be back in a couple of weeks!?"

All the marine dreaded as they were left to themselves in middle of the Calm Belt, infested with deadly Sea Kings. "Please come back Naruto-sama!"

"I think this is far enough," Kurama said as their ship was no longer in sight. "I don't like baby sitting cannon fodders, but should we leave them there all alone?"

"They will be fine as long as they don't go fishing, and I want to weed out all the useless ones before they become a problem," Naruto said and summoned several million shadow clones. The clones filled the area. "From what I understand, Haki is directly related to a person's will, so training with shadow clones should work, but Rokushiki – the 6 powers – is more of physical things, so I will need to train normally."

"You could still get a good amount of battle experience and useful knowledge with the clones helping out," Kurama pointed and leaped off the blond's head. It landed onto the surface of the ocean. "I'm going to train as well. I might not need it in a real fight, but it's still good to know. Tell me the basic of Haki and Rokushiki thingy, and maybe we will spar with them afterwards."

"Alright," Naruto said and explained Haki and Rokushiki to Kurama. He talked about Observation and Armament Haki but left out Conqueror Haki since that one couldn't be learned. Time flew by quickly as the duo learned and trained their new abilities.

– Line Break –

As fist collided with each other, the ocean rumbled, and tsunami formed. Powerful shockwaves rippled the air as black lightning crackled between the clashes of armament haki. Two powerhouses exerted their indominable will against each other until the orange-haired being launched multiple strikes with his nine tails.

"Damnit," Naruto groaned as he leaped backwards to avoid the attack that would undoubtedly leave holes in his body. His vice-admiral overcoat was already in tattered, and the sword he had was already broken long ago. "That is cheating, Kurama! No tails!"

"I don't remember agreeing to that," Kurama snorted and transformed back into a fox. It was more comfortable being in its original form. "Maintaining a transformation while fighting seriously against you is tiresome."

Naruto glared at the fox before sighing. "Yeah, yeah, thanks for the spar. It was good fighting someone at my level."

"No worry," Kurama responded and jumped onto Naruto's head and curled its body into a comfortable position. "It has been almost a month, so I think we should return to the ship. I want to eat something else other than shitty fishes."

"Me too," Naruto chuckled and vanished from the area, leaving behind hundreds of Sea King's corpses littering the ocean. The titans of the sea weren't a threat to the duo, but they were very annoying in the least. They didn't taste like fish either.

– Line Break –

"I'm surprised that the bitch hasn't shown up yet," Kurama growled. It had been another week since they returned to their ship via time-space ninjutsu. The marines were of course shocked to see their vice-admiral appearing on the ship out of nowhere.

"Yeah, that's why the higher up tell me to go fetch her way before they decide to announce anything to the world," Naruto said as he downed another bowl of ramen. It had been a long time since he had one, and it was beyond delicious. Thankfully he had some good cooks onboard, and they knew how to make ramen. "But she will show up eventually or her title as a warlord will be revoked. I was given the power to do so if she refused to cooperate."

"A title that lets a pirate to do whatever they pleased," Kurama muttered.

"Not whatever they pleased," Naruto pointed out and slurped up another bowl of ramen. "But they can get away with a lot as long as it is not directly against the interest of the World Government or the Celestial Dragons."

"Celestial Dragons," Kurama rolled the words with disgust while Naruto shrugged. "The world should be ruled by the strong! Why the fuck are those weaklings at the top!?"

"Maybe the celestial dragons are secretly strong," Naruto deadpanned and put down another empty bowl of devoured ramen. He patted his stomach in satisfaction. "Man, that was good. Being a vice-admiral has its benefits too. I can do whatever I want as long as long as I follow orders. This isn't that much different than from being a Shinobi."

"I highly doubt that. I mean about the Celestial Dragons being secretly strong. And the pays sucks! You know how much I get for being a captain?" Kurama snorted. It learned its rank soon after it returned to the ship, along with the pay grade. Of course, it didn't need money, but it was a monster that could destroy worlds, so it should be paid a lot more than a few hundred Belly. "And another thing, why are there only men onboard? Don't the Marine employs women?"

"They do, but only a handful from what I remember," Naruto said as he recalled all the women he met – or more correctly Momonga met. "And they are pretty strong themselves, at least in the power scale of this world. There are also strong women out there too. Boa Hancock is one if what being a Warlord is all about. One of the strongest women is Big Mom, one of the Four Emperors, or maybe should call her an Empress?"

"Is she hot?"

"No," Naruto replied with a sweat-dropped. "She was though from her first bounty paper. She really did let herself go after having so many kids. Good thing the Warlord I'm going to escort is a babe and single, or I have already reported that she didn't show up and have her status revoked."

"How you know she's single?"

"Just a guess, because of you-know-who," Naruto said and leaned back against his chair. "unless it is netorare – that's could be fun too."

"You're pretty laxed about all of this?" Kurama said. "May I remind you that devil fruits powers are no joke. You should find one for yourself to even the playing field."

"I will once I finish here," Naruto said and yawned. "Lighten up Kurama. It has been a long time since we can do whatever we want, so relax and enjoy a little. Maybe after all of this, we should conquer the world?"

"I like to find the protagonist and see how much plot armor he has," Kurama said with a devilish grin.

"or she has," Naruto said and closed his eyes. Derailing canon was good too since it would give him a lot of points for doing so. Killing the protagonist would give a lot of rewards. "I'm going to take a nap now. Wake me up when something interesting happens."

Nothing really happened for a couple more days until there was exactly one week left until the planned execution. Naruto wasn't told the exact date when he left Marineford to fetch Boa Hancock. He was told later though a communication device that shaped like a snail.

– Line Break –

"Laying anchor right in the middle of this sea of monsters, you certainly have some guts," one of the Kuja pirate said.

"That's because the treaty said we are not allow to go within 3km of the isle of woman," Naruto said, annoyed. These bitches showed up late and started criticizing him. Besides, the only monster in this sea was on top of his head. The Sea Kings were a joke compared to Tailed Beasts.

"And you are?"

Naruto winced. "I'm Naruto Uzumaki, Vice-admiral of the Marine Headquarters. I'm here to greet and escort royal shichibukai pirate empress Boa Hancock to Marineford. Can you call her out now?"

"I'm afraid Hebihime-sama will not be showing herself to you," was the response. That ticked off both Naruto and Kurama.

"You men, you men, you have no grace at all."

"Can I just wipe these feminists out and say we never saw them!?" Kurama suggested.

"I'm inclined to agree with you," Naruto said. "Look. The location and date have been set for the public execution of second division commander of the white beard pirates, what his name, so can you please get your captain out and greet me in a civilize manner because my captain – this guy – do something that we all regret."

Naruto was pointing at Kurama.

"Let me have them already!" Kurama jumped forwards, but one of its tail was grabbed by Naruto. It slammed face first onto the deck, comically.

"See what I mean?" Naruto said before letting go of the tail. "Besides, this assembly is compulsory, so if you guy refuse to attend, the treaty is void and your status as a Warlord will be revoked. And then I have to return here to wipe you guys out. It's so troublesome."

"How many times do we have to tell you this," the Kuja pirate responded. "Hebihime-sama will not be showing herself to you."

Naruto stared at the bitch. "Can I kill her?"

"Negotiation have broken down," Kurama roared and jumped onto the ship. "You are hereby under –

It was promptly kicked overboard, causing Naruto to blink. Even Kurama let its guard down, there was no way it could be kicked like that.

"Who in the blaze had the gall to place a kitten in my path!?" the captain of the Kuja pirate asked.

"Boa Hancock, huh?" Naruto said and eyed the beauty as she looked down at him.

"That's the Pirate Empress Boa Hancock!? Now that's what I call an ultimate beauty!" the marine onboard called out.

"Who are you?"

"Ah… I'm Naruto Uzumaki –

"I have no intention of fighting this war," Boa Hancock interjected. She was not interested in his name whatsoever. "However, I would prefer that you not revoke my status as Shichibukai. Also, I would like you to hand over all the cargo on your ship."

Naruto glared at her before his fury exploded. "What the fuck, you bitch! I'm going to kill you and burn your shitty ship for making such a demand!"

"Hurry up," his men called out as they carried the cargo, including foods, readying to give to the Pirate Empress.

"What the fuck are you idiots doing with my stuffs!?" Naruto growled angrily. His killing intent was leaking all over the place, and the men around him fainted violently as they saw grim flashes of their demise. This caused the Kuja Pirate to become utterly silence.

"Shit!" Naruto cursed and calmed himself. He had accidentally knocked out his men for something so stupid. "Look here, you idiot bitch!"

Boa Hancock winced. She was stunned into silence before because she thought the vice-admiral just use Conqueror Haki. However, she realized that wasn't it.

"The execution is to take place precisely one week from today," Naruto said calmly. "Either you come with me to the assembly or face the consequences!"

"That was a nice swim," Kurama said as it climbed back onto the ship and returned to Naruto' side before shaking its body to remove the water. "Be careful Naruto, they know Haki and very good at it as well. I dodged her kick instinctively, but I was still hit anyway."

Naruto wiped his face and cleared the sprayed liquid. "Did you have to do that next to me?"

"I enjoy my position as a Shichibukai, and I would not want it revoked," Boa Hancock said. "However, I detested the World Government. I refused to comply with their orders."

"I don't care what you want," Naruto snorted. "Either you come with me or I will drag you ass there unconscious."

"Have you not heard," Boa Hancock said. "The marines who were sent to rendezvous with me met a mysterious accident at sea and were eliminated completely. Their bodies turned to stone."

"She's planning something!" the men shouted. "I've heard stories about ships that were attacked by the Kuja Pirates. How they were discovered, drifting at sea with no living soul aboard, only a collection of strange stone statues."

Naruto widened his eyes as he remembered some of the stories. The only thing that could do that was a devil fruit. She was a devil fruit user. "You did what!? Are they dead!?"

"Yes," Boa Hancock answered, "but I will be forgiven. Whether I tear off your ears, kill innocent people, burn villages, I will always be forgiven. Because do you know why?"

Naruto was ticked off. Killing was normal for him, but he would never desire to kill people who couldn't defend themselves. He admitted he was a monster in human form, but he liked to know that he was also human.

"It is because I'm beautiful," Boa Hancock announced. Her face was serene.

The men shouted. The woman shouted. As well as one fox. "Ahhhhhh! Hebihime-sama/Hancock-sama."

"Why the fuck are you affected!?" Naruto shouted at Kurama.

"But isn't she beautiful?" Kurama responded with is eyes seemingly turned into heart.

"Your guilty hearts, entranced by my beauty will turn your bodies stiff as rock," Boa Hancock said and gestured her hand into the shape of heart. "Mero Mero Mellow!"

The men instantly turned into stone, except for one. Naruto had dodged the attack as it passed over his men. He landed back onto the ground. "Did you just attack me? That's a declaration of war, wasn't it, Kurama?"

Kurama was a statue, causing Naruto to drop his jaw. "You got damn perverted furball! Why the fuck didn't you dodge!?"

Naruto grabbed the statue and smashed in against the deck of the ship angrily, causing the Kuja pirate to flinch.

"Have you gone mad?" Boa Hancock asked.

Naruto exhaled deeply and stared at Boa Hancock. "You're pissing me off," he said as red mist erupted from the broke statue that was Kurama.

The essence of an immortal Chakra Beast swirled into a massive ball of energy behind the battleship of the Marine before nine tendrils emerged, forming a nine-tail fox. The beast roared as black sphere formed in its mouth.

"Be gone," Naruto said as the bijuudama slammed into the Kuja's pirate ship. He narrowed his eyes as the ball turned into stone before the impact and broke the ship apart. The crew was set adrift on the sea even though they managed to escape instant death.

"Unforgiveable," Boa Hancock said as she stood aboard the marine vessel. "How dare –

Her eyes widened as pain speared through her body.

"Shut up," Naruto said as he landed a punch into her stomach once he narrowed the distance. His fist impacted against her blackened skin. The godly energy from another world propagated through her body and exploded out of her back, ripping her clothing to shred.

"Ah…" the Pirate Empress coughed and collapsed onto her knees from the pain. He didn't use any Haki and yet, his fist bypassed her armament defense. It was like fishman karate where they utilized water inside a person's body. She looked up at him.

"How?"

Naruto stared down at the crouching woman.

"This is how our eyes should meet, Pirate Empress," he said condescendingly and took note of the strange mark on her back. He instantly realized what the mark was. His lips curved into a smirk. "The most beautiful woman in the world was a pig's plaything?"

– To be Continued –