Haki Power vs. Fishman Power

Luffy came flying in the air.

Luffy summoned a flare of Haki that reach the ground, which didn't affect Arlong.

"Idiot! That won't work!" Zoro yelled.

That didn't stop Luffy as he stretched his neck back.

"Gum-Gum Headbutt!" Luffy yelled as he swing his head forward and hit Arlong in the head.

Arlong was send backwards as Luffy landed on the ground.

Luffy focused haki into his leg.

"Haki Powered Kick!" Luffy yelled as he kicked Arlong toward the building.

But then Luffy grabbed Arlong and pulled him close to him as he stretch the other arm back while focusing haki into it.

"Haki Powered Gum-Gum Bullet!" Luffy yelled as he hit Arlong with so much force.

Arlong was send flying into the air, but Luffy was still holding him as he pulled Arlong close to the ground causing it to crack.

Luffy let go of Arlong.

"Haki Powered: Gum-Gum Machine Gun!" Luffy yelled as he send multiple punches into Arlong, causing the ground to break into a crater with each hit.

Luffy took a time to catch his breath.

Arlong got up, with blood coming out of his mouth.

"You were able to stand 10% of my power," Luffy responded. "I have to admit, you're pretty good."

"Same goes to you! I never thought there's a human that can cause me to spit blood," Arlong responded.

"Well I'm just warming up!" Luffy responded.

"You do understand you're going to die fighting me, right?" Arlong asked.

"I'm not going to die. I made a promise that I will beat you," Luffy responded.

"Hmph! Later you will give up and die. I am so upset that my beloved grew were defeated by worthless insects," Arlong responded.

…

"Go Luffy!" Usopp yelled, "I'll cheer for you from here!"

…

"Those were some hits," Gin said.

"Yes, but it'll take more than that to defeat Arlong," Nami responded.

…

Zoro and Sanji decided to sit the rest out.

"If he lose, all of us will die," Sanji said.

"It could be worse," Zoro responded.

…

"Do you know the difference between the two of us?" Arlong asked.

"Teeth? Jaws? Fascia?" Luffy asked as he stretched his hands with a finger lock palms out.

This angered Arlong.

"Species!" Arlong yelled as he dived in for a chomp.

Luffy dodge Arlong with ease.

Luffy summoned a flare of Haki.

Although Arlong was unaffected and continued comping, Luffy dodge each attack.

One attack Luffy dodge allowed Arlong to bite through a poll.

"This ois the power of the fishman. Since we were born, heaven gave us the power to separate us from you. Humans are lower and weaker than us since the day he was born!" Arlong responded.

"So what? I can punch with enough force and Haki to destroy a whole steel wall," Luffy replied.

…

"He has a point," Sanji agreed, "He did shatter Iron Wall Pearl's armor with one hit."

"And Don Krieg's armor!" Gin responded.

"Not to mention destroyed a cage made out of iron and concrete!" Zoro yelled.

…

"Brother Luffy really did all that?" Johnny asked.

"That's weird!" Yosaku responded.

…

"Humans are powerless species! When you were drowning, you couldn't do anything. So, what can you do now?" Arlong asked going to attack Luffy.

Luffy summoned armor haki around him.

Arlong tried to bite Luffy, but found himself repelled from the Haki.

"What?" Arlong asked.

Luffy punched Arlong's jaw with so much force, it destroyed Arlong's teeth.

Arlong hit the ground in pain.

"Haki armor! Nothing works better in repelling than that," Luffy laughed.

Everyone looked at Luffy a little surprise.

"Let me tell you something! I don't know how to use swords! I don't know how to Navigate! I'm bad with any weapon given to me! I can't lie! I can't cook!" Luffy yelled, "But there's one thing I can do, and that's using Haki! Especially by combining it with my Devil Fruit Power!"

Arlong started laughing.

"I've never thought that you were this worthless. You seem only good at boasting! Your crew must have headaches from you. I don't know why these people have to risk their lives for you," Arlong laughed, "A pirate with no pride like you, is not worth being a captain!"

"I will defeat you!" Luffy grinned.

"Shut up!" Arlong yelled.

Arlong's broken fangs came out and a new set immediately grew in with it.

"Ah! Your teeth grown back!" Luffy yelled.

"Saw-fish can always grow back their teet, and these new teeth are stronger than the old ones!" Arlong responded.

Arlong grabbed his teeth and pulled them out in a form of dentures.

His teeth grew in, and he took them out as dentures again, and again another set grew in.

He held each denture in his hands and chomped them with his hands.

"This is the gift that heaven gave us. So, do you understand how great fishmen are?" Arlong asked.

Arlong came at Luffy chomping the dentures.

Luffy crossed his arms and summoned armor Haki around him and used it to repel the teeth out of Arlong's hands.

"Haki Armor Gum-Gum Pistol!" Luffy yelled.

Luffy punched Arlong in the jaw, breaking the teeth once again, and sending Arlong flying into the water.

"That was easy," Luffy responded.

"Idiot! You punched him into the water!" Zoro yelled.

"Yeah! Why is that a bad thing?" Luffy asked.

A fin appeared in the water, and was moving.

"Is that a shark fin?" Luffy asked.

"No! That must be Arlong!" Gin responded.

"Watch out Luffy! Fishmen move through water better than on land," Sanji warned.

"Yeah, but I can't swim, so it's not like I'm going to dive after him. If I stay away from the water, I should be fine, right?" Luffy responded.

…

"He actually has a point," Johnny agreed.

"Yeah!" Yosaku agreed.

"It's not that simple though," Nami responded.

"What?" they responded.

…

The fin disappeared into the water.

"Now where he go?" Usopp asked.

"This is not good," Sanji responded.

Suddenly Arlong jumped out of the water like a dart being thrown at top speed.

Luffy barely Arlong with only a cut on the shoulder by Arlong's nose.

Arlong broke into the building.

…

"What was that?" Usopp yelled.

"It was like a torpedo," Sanji responded.

…

"That was close! If I didn't sense his attack coming, I would of took a direct hit," Luffy responded.

…

Arlong came out of the hole he created.

"So he can dodge my attacks. No matter! I can defeat him," Arlong said.

…

"Alright! I better go into second gear," Luffy said.

…

"Next level?" Nami asked.

…

"Does he mean…" Usopp responded.

…

"There's more to Haki than what he showed," Zoro responded.

…

"This is the second time I was pushed this far," Luffy thought.

…Flashback…

It was back during the fight against Blue Jam.

Blue Jam had beat up Dadan

"Luffy! Ace! Get out of here!" Dadan responded.

"No!" Ace responded.

"That's right!" Luffy yelled as he ran at Blue Jam.

"Luffy don't!" Dadan yelled.

Blue Jam hit Luffy and send him to the ground.

"Luffy!" Ace yelled.

"I won't give up!" Luffy said getting up.

Luffy kept charging, this time adding Haki.

However Blue Jam knock him down each time.

"Luffy stop!" Dadan responded.

"No! I want to fight to live!" Luffy cried.

Luffy's body started turning red as his skin gleamed in the sunlight.

Luffy rushed in and this time hit Bluejam with so much force that Bluejam was knocked out.

"Luffy, how did you do that?" Ace asked.

"I don't know," Luffy responded.

"It doesn't matter! We got to get out of here somehow!" Dadan responded.

Dadan rushed them through the flames, taking the most burns, until they reached the river bank.

…End of Flashback…

"I didn't understand it back then, but now I have an idea what happened," Luffy thought.

"Shark on Darts!" Arlong yelled.

Luffy body stretch and retract to normal. This caused Luffy's body turned red as started shinning in the sunlight. To add to it Luffy added haki armor to his legs, causing them to turn black.

Luffy turned around and gave Arlong a powerful kick that send Arlong into the building with so much force that the building collapsed.

Everyone watching had their jaws dropped open, including the Straw Hats.

They waited for a while to see if Arlong would come back, but nothing.

"It's over!" Nami responded.

…

"Arlong was defeated," the villagers said.

The villagers cheered as Luffy collapsed with his skin turning back to normal.

"Luffy truly is a master of the Haki," Sanji responded.

"Yeah," Gin agreed, "But why didn't he done that in the previous battles?"

"He was always holding back, I'm surprise we didn't notice it earlier," Zoro responded.

Little did they know, Luffy's second gear was caused by his devil Fruit powers along with his Haki, but still, Luffy was holding back his true power.

A/N: I thought this would be a good time to reveal what happened during the battle against Blue Jam.