One Piece: Unreal Adventure

The giant air slash tore through rocks, and ground anything as it made its way to Garp. But the marine hero stood his ground and just backhanded the slash away like it was fly.

But Luffy was already behind Garp's back with his naginata trying to stab the marine hero. But the marine pinched the blade in between his thumb and index finger with his other hand. "Did you really think that would work, when you are this slow?" And he kicked Luffy away. Taking his weapon. He threw the weapon behind him so that Luffy wouldn't be able to use it.

"Brat stop holding back. Use all your strength, or you might get knocked out before you can." Garp this time didn't move from his spot but cocked his fist back and punched the air hard.

Luffy narrowed his eyes, but it quickly turned into wide eyes when he saw the air force generated from the punch almost flinging him away.

"On your left!"

Luffy was punched to the side as he skitted through the battlefield crashing into the nearby forest, and going through some of the trees.

But he wasn't one to give up as he got out of the mess only to see Garp above him with a punch ready. Luffy quickly used the gear second's ability to skip to the side, missing the punch, which created a large crater on the ground.

Luffy could already see that Garp's hand was black. The boy gulped. "Uh… Hey, isn't using Armament Haki out of the rule."

Garp laughed, "Oh, so you can see it, then. Good, then it will help you avoid it." Again Garp disappeared from his spot, this time Luffy was too late to avoid it as he was punched in the gut.

Knocking the wind and gears out of him. His body returned normal as he crushed through several rocks and trees, creating a dragline in the ground. "*cough *cough…" the boy coughed trying hard not to vomit. "You shitty old man!"

Luffy roared as his muscles buckled as he gained a few inches in height, while his skin turned red and steam came out of it.

"Oh, so you still have some fight left," Garp said, standing his ground with a carefree smile. "Come then… let's see how good you are."

"Fine," Luffy said as he stretched both of his hands backward, his fist enlarging to a gigantic size. Even though Luffy didn't want to use any of the Rokushiki, he didn't want to hold back either. So he used the rubber version of tekkie to make his fist stronger than even steel. "You asked for it. Gomu Gomu no… Giant Silver Gatling!"

"Now that's what I'm talking about!" Garp said as his fist again went black, dawning the color of armament as he did his own fury of punches.

In the middle Silver met Black. And it was obvious who was the winner.

"Ah!!!" Luffy shouted back as he found his fist mangled and bruised.

"On your left!"

Luffy turned but this time the punch came from the right.

"Did you really think pirates would give you pointers in fighting?" that's all Luffy heard before the world turned dark.

.

The next time when Luffy woke up, he was in bandages. But he wasn't in the same place anymore. He was near a small campfire and there was a lot of food that was near him. His naginata was on his side as well.

"Thanks for patching me up, Sparky." Luffy said as he winched when he tried to move his hands. They weren't broken, but he was sure there were multiple fractures in them.

"Wu!" Sparky said as he went into the stash of food and took out a jug of milk from somewhere. And he gave that to Luffy.

Luffy didn't question the logic behind this world as drinking milk somehow cured broken bones or missing teeth. So he just chugged the jug… and he was already feeling better.

"We are not on Dawn Island are we?" Luffy asked the six-armed monkey. The surrounding was definitely different from the one he was familiar with.

The monkey shook his head.

"No, you are not brat." Garp answered, actually Luffy thought that he already left, so he was a bit surprised.

"Didn't you say you have to leave after the fight?" Luffy asked. "Why the change of mind?"

"It's cause of you." The large man said sitting near Luffy grabbing something from the food stash and started eating. "You wanted to become stronger right? This island has more strong beasts that are mostly above your level, so fighting them will make you break through your plauto… But I'm curious. How do you have that… the color of Obersrvation, I mean… If you can master it, it will help you quite a lot."

"Color of what?" Luffy acted stupid. Of course, he was showing signs of Observation. That's how Luffy was able to see Armament Haki. As the definition of Armament Haki was an invisible armor made out of Haki. And one can't see it unless he has Observation.

Of course, there are those that with time and exposure was able to see Armament even if they didn't have Observation haki. It was kind of weird. 

"So you don't know… Of course, you wouldn't. But, you clearly have some talent for it." Garp said nodding. "It's something like a sixth sense where you can read your opponent's intent and be more aware of your surroundings. But the fact that you didn't sense me coming here, means that you are still new to it… you are lucky you didn't awaken it the middle of a fight. Sometimes it messes you up, if that happns."

Luffy could only remember Coby in the canon who awakened his Haki in the war. But it seemed more common than it was let on.

"Anyway, I will come again in a month to take you back to Dawn Island. Try surviving till then."