3rd person POV:

News choppers and drones began swarming the area where Izuku and Jack were fighting. Everyone across Japan was watching as a complete warzone was going on in Mustafar. Slash after slash, Izuku tried to take the Beast Pirate down with him not backing down in the least. A quick slash from Jack forced Izuku to jump up and run over his arm. "DIE YOU INSECT!" A slash from the back was evaded by Izuku to get right at the pirate's face.

"STRIKE OF THE VENGEFUL TIGER!" Izuku let loose a strong attack on Jack's face to slide him back. Unfortunately, this did little as Jack soon recovered and came charging at the Green Demon once more. The two connected blades with the sheer strength of Jack alone forcing Izuku to lose ground.

"What are you, boy? Are you a pirate? A hero? A swordsman? I'll tell you what you really are." Jack gave a knee to Izuku's stomach to send him back into a building. "YOU'RE NOTHING! JUST THE LINGERING CRAP FROM THE WORST GENERATION! YOU CAN'T EVEN FATHOM THE LEVEL OF POWER YOU'RE FACING RIGHT NOW! SO DIE AND DON'T ANGER THE BEAST PIRATES EVER AGAIN!" Jack came for Izuku's neck with his blades to have him dodge and see the building that he was blown into fall to the ground.

"Cheap shoting asshole! You honestly wanna attack me like that knee jab? Do you have any respect or honor whatsoever!?"

"Respect? Honor? Those things are useless on a battlefield. They only limit you and make you weak. The ability to go all out is truly what matters. NOW DIE!" Jack gave another barrage of slashes for Izuku to dodge them using Observation Haki. "IS EVASION ALL YOU CAN DO NOW!? WHAT HAPPENED TO THAT BRAVADO YOU HAD!?"

Izuku was able to get under Jack to slide between his legs and take an attack to the back of his knees. "If you refuse to show me the honor of a fair fight, then don't be angry if I choose to fight a little dirty as well!" 'I need to finish this and lighten the blow to the people around here. It's too dangerous to drag out a fight with this guy.' Izuku was about to strike, but Jack gave an attack to counter and sent Izuku into another building.

As the dust cleared, Izuku was holding a defensive position with his swords to show he was able to block the blunt of the attack, but his arm was notably cut to surprise Jack. "You're more durable than I thought. If you're in one piece, then you must've been able to block my attack. Not a lot have that to be proud of."

'He's right. I couldn't block the whole thing, but if I didn't switch to defense at the last minute, I'd be cut clean through.' Izuku let out a sigh to calm his nerves. His tenseness though wasn't from nervousness or fear. It was excitement. Very rarely does Izuku get the privilege to fight opponents in a battle that puts his life in jeopardy. Now, he's facing the exact scenario he's regularly dreamed. "Alright Jack, I think it's time we take off the training wheels and start fighting seriously." Izuku smiled as he placed Chujitsune in his mouth while also placing Muramasa in his hands. "Three Sword Style: Twin Demon Technique."

With the crew

As Izuku handled Jack, Itsuka and the rest of the crew pushed back the Beast Pirates and tried to take the students and dojo's master to safety. "Your captain's an idiot! Thinking he'll take on master Jack and live? HE'S GONNA DIE LIKE THE REST OF YOU!" The man's hand turned into a wolf's head to try and bite Perona to have her create a giant Hollow and blow him back.

"If your boss is so strong, he wouldn't be pushed back so easily by our captain Horohorohorohoro!"

"WHAT TYPE OF FUCKING CREEPY LAUGH IS THAT!?" Bakugou shouted with Perona immediately taking offense to it. 

"IT'S MY LAUGH! IF YOU THINK MINE'S CREEPY, THEN HAVE YOU LOOKED IN A MIRROR WHEN YOU START LAUGHING MANIACALLY RECENTLY!?"

Itsuka kicked a Beast Pirate a distance before turning to the two. "Now isn't the time to be fooling around like this! We have a serious problem on our hands! Izuku's about to use an attack that's going to be detrimental to us all!"

Everyone was confused with Ochako knocking another Beast Pirate down. "What do you mean?"

"To make a long story short, Izuku found a way to make a skill that's so dangerous that it's only going to be used when he has no other option." Sending a few Beast Pirates away with wind, Itsuka pointed at the newly positioned blades. "In one hand, he holds a blade who's fire ignites to burn the body. In the other, a blade who's fire can cleanse the soul. The power of both used at the same time will cause anyone to go mad. If we don't get out of his slashing range, we're all going to die."

"I'VE GOT YOU NOW, BITCH-" Itsuka used the bottom of Fujin to hit the pirate attacking in his family jewels.

"I'll explain as we get out of here, Marguerite! Cover!" The amazon woman agreed to begin aiming at the Beast Pirates to take down any that came close. "Master! Can you stand!?"

"I can. Let's go everyone. Leave this to the adults." The children ran away in hopes to avoid getting involved with Bakugou making a hole through the Beast Pirates.

"GHOST GIRL! MAKE THESE GUYS DEPRESSED!"

"I HAVE A NAME!" Perona shouted in anger before she made several Hollows. "Negative Hollows!" The ghost entities went through several of the Beast Pirates for them to fall to their knees. "There. That should do it-" The Hollow Fruit user was pushed back by Ryukyu who used her leg infused with Haki to block another attack by a man with a crab's hand. "Thanks."

"Focus on the fight. These Beast Pirates ate Smile." Hado blasted a bunch of pirates away who were being replaced in drones before asking about it.

"What is that? Some kind of power up drug or something?"

"To make a long story short, it's a man made Zoan Devil Fruit. It can allow the user to make any part of their body that of an animal's." Ryukyu knocked the crab claw Smile user's hand up before giving a swift kick to the face and knocking him back. "To make a long story short, it's a power that should've never existed in the first place and is an abomination of nature."

"So how do we tell if they ate this Smile or whatever it is?" Amajiki asked while having a Smile user bite off his octopus tentacles with a wolf's head before Mirio knocked him out.

"The Smile user's have horns on their heads. Very strange ones that make them look like devils."

"PATH'S CLEAR! GET EVERYONE OUT OF HERE AND FALL BACK, NOW!" Momo shouted with some fear in her voice for everyone to run out  the opening to the city.

Once safe enough away from the real fight, Itsuka looked at Momo who was notably shaking. "Momo, take the kids and master somewhere safe. This isn't a safe spot to stay."

"Understood." The dark haired girl led the kids of the dojo as far away as possible with the rest of the group staying where they were.

"So you wanna tell us what the fuck Deku's doing?" Bakugou asked for the orange haired woman to point to a rooftop.

"It's better if you see it to believe it."

With Izuku

Izuku began panting with a smile on his face to confuse the Beast Pirates and Jack. "That's a stupid look you have. What the hell are you trying to pull here?" Izuku didn't answer with his breathing growing heavier and heavier. "HEY! I ASKED YOU A QUESTION!"

Izuku calmed his breathing before slowly looking up to Jack. In that moment, an unsettling chill went down everyone's spine as Izuku's image in their eyes altered for a moment to show a black figure with a sinister smile before returning to his own image. "I hope you had your fun, Jack. Because you're about to become one of your own disaster sites."

'Am...am I scared?....I'm scared, of THIS BRAT!?' "YOU THINK I GIVE A CRAP WHAT YOU JUST DID!? YOU'RE STILL NOTHING TO THE MIGHT OF THE BEAST PIRATES! MEN! SHOW HIM WHAT I MEAN!" Several Beast Pirates began circling around Izuku with desire to kill him shown in their eyes for Izuku to simply smile and laugh."

"What's so funny, kid?"

Izuku's body began swerving from side to side as he hummed to himself. "I'm just laughing at the fact you all believe that I'm going to die here, when you all were already cut at least a dozen times." The Beast Pirates noticed a large amount of blood on Izuku's blades that weren't there before as well as a sudden immense pain in their own bodies to have them all drop to the ground and scream. "Demon Blade Art: Zone of Death."

"What did you do?"

"Nothing really, I just showed them why my name is The Green Demon." Izuku stated this as a small cut was on his face to trickle some of his own blood down.

With the crew

Everyone watched in shock and horror as Izuku took down over a hundred pirates too fast for anyone to see. "Just what the heck just happened? Midoriya didn't move, but everyone's on the ground from cuts and his blades are covered in blood."

"It's a final technique he knows, Kaminari." Itsuka looked pale as she explained. "Demon Blade Art as he calls it, Zone of Death. A technique that moves so fast that the human eye can't even see what's happening. I doubt someone with Haki could see what really happened completely."

"I saw fragments, but I thought I was seeing things." Ryukyu looked astonished as she stood in disbelief with everyone on a rooof top.

"That's amazing. He's so fast that nobody can keep up." Tsu spoke up before seeing Izuku with a few cuts. "Why are there cuts on him though?"

"That's the flaw of Demon Blade Art. Izuku moves so fast that he can't tell what or who he's cutting. Anything within a ten meter radius of him is slashed at and indiscriminately at that. We found this out during one of our training sessions with the Straw Hat Pirates. Basically when it happened, it took Luffy, Zoro, Sanji, Franky and Chopper in his Monster form just to hold Izuku down and keep him still long enough to let go of the swords. The thing that scared both me and Momo wasn't the fact that it took so many Straw Hats to hold him down, it's the fact they might've actually not been enough if they didn't catch him in time." Everyone's eyes widened at this with Ochako looking out to Izuku for a few moments.

"Why did he change what swords are held and what aren't?"

"My best guess, because those two are more likely to help end the battle quickly. Nonetheless, Izuku right now is no different than a demon and going near him is a death wish."

As the group watched, Jack began to fight back against Izuku. "You think just because you have some strange new skills you're a big shot now? YOU'RE STILL NOTHING KID-" Before he could finish, a strange and painful slash was felt on Jacks left hand. Looking down, he was mortified as the hand he once had was now a severed limb. "AAAAAHHHHHH!!!!!"

Izuku continued to walk towards Jack with  his eyes glued to the Beast Pirate. "Your days of terrorizing the world are going to end here, Jack the Drought."

"SCREW YOU! You think I give a damn about what you think!? You're dead meat, JUST LIKE THE FOOLS BEFORRE YOU-" Izuku was no longer in front of the Beast Pirate, but instead behind him.

"It's over. The injuries I inflicted on you are now too great for you to handle." Izuku placed his blades in their sheaths and waited calmly for Jack to turn around.

"THE HELL ARE YOU TALK...." Jacks body began to feel weak, in pain, and most of all, cold. Looking down at his body, cuts began to show that were enough to make it a marvel how the pirate was still in one piece. "GAH!"  The face covering of Jack broke to show him spewing blood before falling to his knees.

"Thank you, Jack the Drought. If it wasn't for you, I wouldn't know my own limits with this technique." Just like Jack, Izuku's body began to show similar cuts before falling back himself from the pain and blood loss.

"IZUKU/MIDORIYA!" The crew saw both fighters fall for them to head down to the ground as fast as they could. Ochako, Itsuka and Tsu grabbed Bakugou with the earlier making the three weightless to make traveling by his explosions easier to be the first down on the ground.

"Is he gonna be ok?" Ochako panicked while seeing Izuku in a pool of his own blood.

"Stay back!" Ryukyu came over with medical supplies to immediately rip the green haired man's shirt open and begin cleaning the injuries. As she did, she noticed some healed while others were burned shut. "This is peculiar. Most of the injuries are either healed or burned with the bleeding stopped."

"That must be why Izuku changed swords, then."

Bakugou stared down at both blades to see one burn blue and the other red. "Using one that burns anything with blood contact to burn his injuries shut, while the other heals and regenerates to  help prevent any quick prolonged damage to some degree. Deku was pretty smart in how he handled this." Bakugou soon turned to Jack who could barely even move from his own injuries. "So what should we do about horn guy here?"

"I'll put in a call when we get back to the ship. For now, the best course of action we can do is stabilize him." Ryukyu finished what she could before looking at Itsuka. "Can you fit Midoriya in your hands and carry him slowly towards the ship?"

"I've got this." Itsuka's hands grew to hold Izuku in them and begin heading out of the area. 'Don't worry Izuku. You did your part, so let us do ours.'

And that finishes this chapter. See what happens next time with Izuku and the after effects of this fight. Hope you all enjoyed and thanks for reading.