Steelborne

(Alright, I did some research and need an opinion. Not a hundred percent is sure if the opponent from the underground had a Kekkei Genkai or a hidden technique. I would imagine that manipulating keratin would be a Kekkei Genkai, and not something that would be copyable, but I'm not sure if some would consider it a hidden technique. Because Haku's ice release is a Kekkei Genkai and this is similar but I'm not sure, please help. Plus a lot more people in this book will probably have a weird ability so if someone could help explain the difference it would be greatly appreciated.)

Naruto groaned as she woke up. She remembered how tough that training was yesterday, and even with her enhanced regeneration, she would still be sore for a couple of hours. Luckily, they had the underground match this afternoon. Naruto yawned as she slowly rose out of bed and didn't bother changing out of her pajamas, she pulled herself to the kitchen where she put together a simple breakfast of rice with an egg on top. She lazily threw her hands up in a cross position as she pumped a load chakra through them, a clone popped up beside her and only silently nodded to their master before throwing on their signature orange sweatshirt. Naruto would just have her clone transform but then if something happened, like it getting spilled on or dirty, it wouldn't appear on the illusion and therefore people would get suspicious.

Naruto watched as her clone ran out the door to head to the academy. Naruto got up and headed to her room, she had a couple of hours before she needed to head to the underground, but first, she needed to check her winnings from last night.

She went to her room and opened up the drawer by her nightstand, she quickly took out all the useless things she had stored in there, like glitter, hairbrushes, and other things, and pulled out the fake bottom. She created this a long time ago when she first wanted to become a ninja, she wanted to pretend to have her own secret base, and it stuck with her ever since. Not that anyone would even dare get near the demon's home. She still remembers watching the disgust on everyone's face as she moved in, and her waking up to an empty neighborhood the next morning.

The trapdoor was pulled open to reveal a scroll and the cultivation book. Naruto had... borrowed a sealing scroll after she learned to properly use chakra the other day. The owner of the store was a bitch, he deserved it and nothing you could say would change Naruto's mind. Naruto grabbed the scroll and the book, as she planned to cultivate until she had to leave. She opened the scroll and instantly stacks upon stacks of Ryo flooded her room. Naruto's eyes widened, 'Holy shit! This could last a year even with the village's bullshit prices they set for me. I didn't realize how much this was even with the clone's memories! I guess being underestimated is truly profiting.' Naruto laughed to herself. She thought of buying that orange scarf and orange shoes she had really wanted, or the really fancy orange jacket, unlike her current ratty one. She quickly set aside a good portion to bet on tonight's match before sealing the rest into her storage scroll.

She opened her book to remind herself what she had to do next, "So large attainment in my visceral training is my brain and lungs. It says that the brain will significantly increase my reactions, memorization skills, and nerve responses. While the lungs will give me much higher endurance and allow more oxygen to go to my muscles. Both of them would be good to help me, but I think I should focus on the brain." Naruto noticed a note on the bottom of the book, she grimaced as she saw the message. 'Warning, infusing chakra into the brain is painful, and if the user loses consciousness during this process, death is not far.' Naruto closed her book and put it with her scroll back into the secret compartment. She quickly changed into a new set of more comfortable clothes, a plain black tank top, and shorts, before sitting down on the floor and getting into her lotus position. First, though, she made a clone to warn her so she didn't get too absorbed and be late. As she sat, she felt the natural energy in the air and slowly started sucking it into herself, and guided it along her chakra veins straight to her brain. She took a deep breath to calm herself before slowly starting to let it leek in.

Naruto almost instantly fainted, she knew it would hurt, the book even said so, but this was worse than the first time she cultivated. It felt like her head had just been split open like a watermelon, but she kept herself in the lotus position, she felt something warm trickle down her mouth, slowly dripping onto her leg. 'Must be my blood, I bit my cheek a little too hard when the pain started.' She thought in her head.

Eventually, the pain started to subside, and it instead felt like a nice massage on the head. Naruto guessed this was due to her brain finally getting strengthened enough to not feel like it was being split open. Naruto slowly settled into a comfortable pace of slowly leaking the chakra in to strengthen her brain. And as she was doing it she was slowly going over her moves from yesterday so she could hopefully execute them properly during her fight.

Naruto was suddenly interrupted by a slight weight on her shoulder, she stopped her cultivation and opened her eyes to see her clone tapping her shoulder. "It's time to go." Her clone said, she nodded. "I see you used the secret move I recommended last time, you don't really have a trump card now, other than shadow clones. But you know how risky revealing that would be." Naruto slightly grimaced at that.

"But I can load more through my body to give my opponent a surprise," Naruto commented, her clone looked at her like she was stupid.

"You do realize we share memories, I saw what ten percent did to us, anything over that and we will explode, even with the nine-tails healing factor on top of our own naturally high healing factor and the natural energies healing. Our muscles can't handle that kind of pressure. Our chakra is also rapidly increasing, we have just started our growth spurt. This is when you can truly start to see the difference between academy trainees and civilian kids." Naruto flinched at the thought of spontaneously exploding. "The only other trump card we have is the nine-tails chakra. We can only draw out tiny bits of it though, and it will look very suspicious so I advise to not use it unless we are in a life or death situation."

"I know that, why do you think we wear this hood, enough people hate my existence above ground," Naruto grumbled out. She changed into the gear she prepared for the underground, before swinging her dark black cloak over her, obscuring her features. Her clone copied her before also putting on their dark cloak.

Naruto quickly shadowed through the backstreets of Konoha, making sure to avoid everyone, and arrived back at the bar that the entrance was located. Similar to last time, she waited in line and was greeted by Iketa. The man only nodded to her, a sign of good luck, as she quickly entered.

She was greeted by the grand view that amazed her last time, the long stretches of buildings and beautiful, glowing crystals that hung from the ceiling. Naruto quickly made her way to the large coliseum determined not to be super late like last time so she had time to prepare herself.

As she was walking by, a couple of people who saw her must have recognized her from the last match. A few of them waved at her and Naruto's social awkwardness kicked in from years of being alone, she stumbled over herself in confusion and did an odd wave that a couple of people laughed at. She was burning red from embarrassment by the time she arrived at the stadium.

She arrived in the waiting room and quickly found a room in the room. She sat down and calmed her down and started waiting.

An hour passed by with people going out to the stadium to start. There wasn't really anyone interesting in the batch that went, though.

"Raymen and Steelborne, please come to the field!" She heard the announcer's voice reverberate through the stadium. Pumping herself up, she stood up and exited the room onto the field. Entering the field she was just as stunned, the huge amount of people, the large field, and that stunning crystal that hung right above them.

Naruto looked across from her to see her opponent, a large man with a black tank top and pants. He was buff, like a bodybuilder, and had a black buzzed haircut and sharp eyes that were a dark blue. The man was very intimidating and the way he seemed to radiate the feeling of being a sturdy mountain didn't make it better.

"Another amazing matchup, Raymen, the mysterious new contestant with speed and power, up against Steelborne, another mysterious contestant that is seen as the sturdy mountain with his amazing hidden technique that he uses to blow away the competition. Remember crowd, bets are starting now, put 'em in!" While everyone was scrambling to bet, Naruto and her opponent were sizing each other up, Naruto wasn't confident she could win, but she would go down fighting.

"Alright, time to begin. The battle between Raymen and Steelheart will now begin!" No one moved, Naruto wanted to see what this guy's amazing ability was, but she could also tell her opponent wasn't moving anytime soon due to his stance. She decided to move in first, quickly circulating her chakra into her legs, she went flying towards him in a burst of speed.

Naruto quickly closed in on her opponent and aimed straight for his left cheek, her instincts were telling her that this was a horrible idea but she needed to figure out his special technique. She had seen this man's match previously, but his opponent was pathetic and she didn't get any idea of his true strength or ability. Right as her fist was about to connect, the man's skin took on a silverish tint and quickly hardened, her fist connected with the hardened skin and a resounding thump rang through the arena. She didn't even see him flinch as she punched him, her eyes widened as she realized the compromising positions she was in, but the man's face turned into a smug grin as she felt the force of a semi-truck plow into her stomach. The man had hardened his fist and punched her in the stomach, sending her flying back and rolling, coughing a bit of blood up along the way. Naruto unsteadily stood back up and wiped a bit of blood off of her lip.

"And there it is! Why they call him Steelborne folks! His special technique to harden his body to the strength and density of steel makes him the mountain of the battlefield. It looks like Raymen has already taken a large hit though, can they win!" Naruto gritted her teeth, she wasn't going down this easily. She quickly ran back at him and got the first position of Hakucho no Odori. Throwing a kick at his side, she watched as he hardened his skin again and threw a fist at her on the counter. She quickly parried the fist by slightly tilting it out of the way and had it breeze past her face. She quickly brought her other hand to hit his stomach and knock him back, but Steelborne also hardened his stomach. 'Damnit! I thought he could only harden one part at a time.' It was too late though as the man brought a hardened knee up and struck her face, sending her flying back again.

Naruto landed and spit out the blood that filled her mouth, as her regenerating powers came in and quickly healed her split lip. She brought her hand up to her nose and everyone heard a sickening crack as she popped it back into place. "So you are as durable as I thought you were, most people would be knocked out by now. But with your puny strength, you won't be able to break through this mountain." Her opponent boasted. His voice was very deep, but also slightly husky, Naruto could tell he smoked because of the huskiness.

"Is that a challenge," Naruto answered back, her voice slightly odd from the still healing lip. The man only grinned at that. 'I don't see a way to take him in head-on combat. Currently, I'm not fast nor strong enough to break through his defenses. I have shadow clones but I would prefer to save those until I know I can't have a chance without them. They are my final trump card after all. And I don't want to pump up to ten-percent again, because if he tanks it I will be vulnerable and he will get an easy win. Think Naruto, think!' Like a lightbulb, Naruto suddenly thought of something amazing, though.

Once again, she charged straight at him, but instead of keeping up the charge, she suddenly started running circles around him. She made sure to stomp on the ground to throw up debris and cover herself in the dust cloud that quickly surrounded her opponent. She could tell he was trying to keep track of her barely visible figure, but he was failing. Seeing that he no longer could see her, she spun on her heel and went barreling toward him, she was behind him and about to punch him in the back of his head, until she caught the silver sheen cover the spot she was about to hit. She quickly tried to change course but was caught in the stomach by a spinning roundhouse kick launched by Steelborne.

Sent flying once again, Naruto tumbled along the floor. She was tempted to not stand up, she had tried and it was like he had a sixth sense, it was impossible to break through his defense. Before she remembered something from Iruka's many lectures. About how some people had the ability to sense chakra. She only remembered this particular lecture because she had been tied up on a chair in the front as punishment for a prank she pulled and was forced to listen through the whole thing. 'Well, it's this or nothing.' She thought as she once again struggled to her feet. Her chakra running out from continuously healing herself quickly and boosting her body.

"I'm surprised you haven't given up, I have proven to be an unshakable mountain for you, yet you persist. It is quite amazing if you ask me." Naruto ground her teeth together hearing this, what an arrogant bastard. She quickly flew toward him and made a duststorm surrounding him once more. "Foolish, the definition of insanity. Trying once more even after failure, you should just give up." She ignored him, before picking up a rock and loading it with her chakra. She chucked it at the man before running at him from another direction, but instead of boosting herself with chakra, she used her own body strength to run at him. She made sure to suppress her chakra as best as she could, so he would lock onto the rock instead of her. She observed as he hardened the area around the destination of the rock, and grinned to herself as she punched him in the side, pumping chakra into her arm last moment so he couldn't react, and sending him flying.

Steeklorne slid back, making sure not to fall before he eventually stopped. Naruto could see him holding his side and could tell she had finally done something. "So you've figured out my weakness, but now how will you capitalize on it." Her opponent claimed with a smug grin on his face. The man slowly picked up the pace and started sprinting towards her, before he got into position to launch a punch. 'So now that I know his weakness he is going on the offensive.' Naruto thought, before quickly getting into the beginning stance of her taijutsu pose. She quickly deflected the fist, only using chakra in bursts at the end of her movements. 'I can't use it consistently, or he will be able to detect all my movements.' She observed.

This skirmish lasted a while, with Steelborne landing a few hits and Naruto returning them before they finally separated. They were both panting and running low on chakra, and while Steelborne's body was littered with bruises and slightly fractured bones, Naruto's body was steaming and overheating from continuously regenerating from his powerful blows. Naruto could tell he was running out of stamina faster, probably due to her ungodly chakra amount and near-infinite stamina. And that was probably why he had separated. 'Thank god for Hakucho no Odori, if this wasn't a defensive stance that focuses on parries but an offensive stance, I would be laying in the infirmary unconscious long ago.' Naruto thought. 'He must be preparing to use most of his chakra in a final all-out offensive.' Naruto got into her stance one last time. And she observed as her opponent got into his position before he barreled towards her, at a speed she didn't expect.

'I didn't think he could be this fast!' She exclaimed in her mind as she watched his shoulder take on the silver sheen. 'Damnit! I don't have enough time to dodge!' She quickly brought her arms up in a defensive position and pumped her chakra through her body to try and strengthen it to defend herself. She felt the impact and the blinding pain in her arms as she was sent skidding back. She loaded chakra through her feet to somehow stick them to the ground, she had heard of it before but never attempted it before. Her feet stuck but that just made sure she tore through the floor as she was sent skidding back. Eventually, she slowed down and came to a stop, as her arms dropped limply to her sides. She could already feel them painfully regrowing the broken bones and fixing themselves, but she held in her scream of pain.

Across the field, Naruto watched as Steelborne finally dropped from chakra exhaustion, she would've thought he was dead if Iruka hadn't taught them of chakra exhaustion and what happens.

All was silent before the audience broke out into cheers and applause. "What an amazing match folks! And we have our winner, Raymen." Naruto heard the announcer state, she grinned to herself happily before finally walking back to the waiting rooms in triumph over the hard match.