Chapter 4 - Mato

Yuuki found himself in an inverted world where it was vastly desolate where only sharp rocks and miasmic air was seen. He looked into the sky and saw it had two moons pondering what this dimension existed and if there are other replacements like this. Yuuki was already researching any information about the Mato dimension but most were quite vague and mysterious.

He wasn't that worried since his goal isn't to end Mato if anything it does help humanity from turning on itself. Yuuki doesn't have any hero complex since he is an outsider and can tip the balance of the world if he decided to truly end it and this will ruin the fun. He took a deep breath and flew into the sky looking around trying to see if there were any more shuuki.

His eyes caught a few people being chased by shuuki and sensed something more powerful. With a sonic boom flew straight at the center of the fight where ripped through the shuuki chasing down the people who were quivering in fear.

"All of you, just head straight and don't look back!"

Yuuki shouted having a voice change function to hide his identity ignoring their shocked faces and continued to mutilate the Shuuki who were surrounding him and even former larger versions of themselves. He was still in his Ultra-Instinct state and rapidly improving since the amount of shuuki was vast, around a few hundred.

"Damn, I guess I should keep up the pace."

He calmly said taking a different stance than normal where his heart pulsating pumping even more blood and his Ultra-Instinct state helped in utilizing his next technique.

[ Exploding Heart Released Fist ]

The exhilarating sensation pumping through his body made him feel alive and his strike caused a more devastating blow where the force exploded inwards. Yuuki could easily fly but preferred to run as it pumped his blood as he jumped into the Shuuki's large arm and ran towards it head while he slice it using [ Whirlpool Iron Cutting Fist ] then when he how've hover it's shoulder was when he clenched his fist then strike the monster disintegrated it's entire head from the forces of his fist.

"What a great warm up! Still wish there's more I can fight."

He remained in the air looking at how they weren't anymore shuuki was and removed his Ultra-Instinct as he was already going past his limit since he was still a child taking deep breaths before continuing his way deeper until he spotted a different kind of Shuuki that was certainly stronger than the rest.

[ Water Stream Rock Smashing Fist ]

Yuuki landed where the unique shuuki was about to strike a girl, redirect its attack and send it flying but surprisingly manage to stabilize itself. He saw that new shuuki had a massive and muscular Shuuki who wore a suit of armor not too dissimilar to a samurai. He also has a massive underbite and a single long horn.

'Wait….isn't this…'

His eyes widened upon realizing something turning around looking at fhe quivering and fear stricken little girl that had short silver bob cut hair and has bangs on the side of her forehead, in the center while two chunks reach her shoulders and pink eyes where her eyes appear slit. She has unique accessories on her ears that resemble flat, blue, curved horns that stick up from her hair.

'Kyouka Uzen…'

"Watch out!"

She shouted as Yuuki instantly countered and defended himself where he's opponent was physically superior than him feeling his attack produce a powerful force but was not utilizing every ounce of it properly.

"Feisty ain't you!?"

Yuuki enjoyed their time and prolonged it as much as possible trying to grasp his own strength. On the other hand, the little girl who would grow up to be the main heroine of this story watched in awe looking at someone who was the same or older than her fighting the monster that took her friends and family.

She was unable to see them move at how fast they were going and her eyes locked on them. Kyouka thought that if she had this kind of power then her friends and family wouldn't have to protect her.

Yuuki took a defensive approach fighting the horned opponent and amazed how his unique shuuki slowly learned upon his own.

'This bastard is copying me ahahahah.'

He didn't feel any problem with an enemy stronger; this only meant he hadn't reached his limits. Yuuki raging heart and viltrumite blood was heating up and testosterone flooded his body and grew even further where the monster managed to strike him several times but each time was counted by Yuuki.

"Yes!! Give me more!! Come at me, Shuuki and let's try to kill each other!"

"Rooaared!!!"

Yuuki planted his legs into the ground then cucked his fist before an explosive force resulted in the unique Shuuki to be sent flying but while in the air Yuuki appeared and grabbed its faces then slammed it into the ground before throwing him away.

The unique Shuuki stopped itself creating a small crated form the impact before leaping toward Yuuki striking his face tanking it causing the mask to slightly crack revealing the side of his face where he's mouth had blood dripping down yet he was grinned that shook the unique shuuki to its core unable to understand why a human still smiled like this.

"HAAHHAHAHA this is what I've been craving for!! My old world was really boring and this truly makes me feel alive!"

Yuuki had many options to truly enjoy the thrill of combat but chose a random world hoping it would give him the most difficult world and found that this world is at least reasonable. Not to mention, they were women that he liked to have though becoming a slave is off putting but the reward in the end is worth it.

The killing intent made the unique Shuuki cower in fear and gave everything it got in escaping his grasp. Normally, it would submit to him since he's stronger but the fear overwhelmed it and vanished from his spot making Yuuki blink for a moment.

"WHAAAAAT!?"

He was dumbfounded that his prey would run away from him and felt incredibly disappointed deeply sighing then suddenly sensed another shuuki was coming and was about to attack Kyouka, closing her eyes thinking she was going to die when nothing happened and heard a robotic voice.

"I guess I can't fight with you around…"

She saw him rip the shuuki to shreds while the one horned was nowhere to be seen. Yuuki decided not to think too hard since Unique Shuuki still has its use for the future and would be better if he grew stronger and switched his attention to Kyouka considering she has a vital role in the future and couldn't go all out in fear of harming her.

"Hope you don't mind me doing this."

Kyouka was in a daze looking through his mask showing half of it where he was able to see his sharp yet comforting gaze and taken aback when he picked her up in a bridal carry And blushed a bit. Yuuki ignored it since she was still a little girl and said.

"Hold on tight."

He felt her arms wrapped around him and prepared herself as Yuuki rushed towards the entrances to let the Anti-demon corp that had arrived to assist her. He flew into the sky then it didn't take long for them to arrive where the antidemon corp was nearby and he didn't want to meet them.

"Sorry but this is as far as I can go."

Kyouka looked at him and didn't want to let go, still scared at what happened.

"P-Please don't leave me."

Yuuki knew that she was having a traumatic experience and clinging to the only version that possibly protected her and that was him but he couldn't stay for long when things had yet to unfold the way he intended.

".....what's your name?"

He asked, surprising her then quickly replied.

"K-Kyouka Uzen."

"What a beautiful name."

Kyouka seemed to enjoy hearing the compliment before feeling her losing gripped lo as Yuuki forced her to let go and panic trying to hold him but couldn't fight back.

"...Call me Kuro oni."

He doesn't know what alias he should name himself and decided on the name that his old gang called him. Yuuki did like it since it was similar to Shiro Oni, a title for Gun Park from Lookism who was absolut monster Rin combat.

"I can't take you where I'm going but remember that you survived for a reason and use this chance to get stronger."

Kyouka couldn't say anything when she was knocked out by Yuuki and flew into the sky where he watched from above making sure that the Anti-demon corp arrived where they saw her unconscious and quickly went to save her.

Yuuki simple interaction will surely be implanted into the depths of her heart and thought that by saving invertedly will cause Kyouka to fall for him or at least feel a sense of debt. He noticed someone powerful in the Anti-demon Corp accompanied them and didn't want to stick around even if he was tempted to fight them felt it was not the right time.

He then resumes his journey to find Peaches to test on himself and the Anti-demon corp carefully brings Kyouka back to earth. Meanwhile, Fubuki and the other Anti-demon corp members couldn't believe finding the remains of Shuuki having even been killed the same way as the one outside.

"It's the same as outside…have you found anything in the area?"

"None so far, Chief. It appears that whoever was responsible had already left."

Fubuki frown decided to investigate this unknown assailant more and saw the sleeping Kyouka where her intuition told her that she might have a piece of information about this person. After a while, Kyouka woke up in the hospital and the other Anti-demon corp questioned her encounter mentioning Yuuki's alias that intrigued Fubuki pondering who he was.

"According to her statement, he moved faster than she could see and fought a unique looking shuuki on his own showcasing a power that ripped the shuuki to shreds. She also said his mask had been broken revealing a black haired boy around the same or older than the little girl we've saved. This unknown individual seems to call itself….Kuro Oni."

"Kuro Oni?"

Fubuki repeatedly found the name to be childish but fitting seeing the aftermath that the young boy had done. Her smile grew thinking that if it's a human boy who is able to display this kind of power that shouldn't be possible since only women are capable of exerting this supernatural strength meant he would be a fine addition to her family.

However, she would have to judge him first and if he is up to standard then she'll take advantage of it for the sake of their family's future.

"That's all we've got."

"Alright, secure the area and see if there's any more survivors. Eliminate the remaining shuuki as well."

"It will be done!"

Her subordinate said leaving her thinking about this newly arise powerhouses wanting to hide the information about it but thought it only a matter of time until it's reveal and gave up on the idea.

===========

While the Anti-demon Corp were busy helping the people, Yuuki was flying through the air searching for the peaches and killing Shuuki along the way until he finally spotted one and flew straight to it. He was now looking at a unique looking peach that exudes power, curious what will happen to a Viltrumite who are superior to humans.

[ Be careful, you won't die but it certainly will be incredibly painful. ]

Ivory warned him while he plucked the peach and took deep breath thinking how to use the peach. The ability is based on the background and emotion of the person. He thought to himself what he desired most and that's to fight.

'Well, whatever, let's just eat.'

He took a bit of it ignoring the risk and upon tasting the peach was amazed that it tasted like normal peach. It was then his eyes widened as he felt energy flowing into his system causing him to drop the peach.

"Gaaaaaaahh!!!!"

Yuuki roared, feeling the excruciating pain where his body was being damaged endlessly, burning away his clothes from the raging energy as his flesh was constantly being destroyed and preparing itself. His eyes were now bleeding in blood and gritted his teeth yet it turned into a grinned until a burst of laughter was heard.

"Yes!! Pain!! The mark of weakness leaving my body!!!"

He insanely shouted then began to control his breathing and energy using the principles that [ Water Stream Rock Smashing Fist] had where Garou use it to stop OPM God from controlling him like a puppet.

Yuuki slowly manages to control it, placing it in the center of his abdomen, treating it like a small universe where it swirls within him until it becomes one with it. After exactly 2 hours that felt like an eternity finally exhaled deeply and his entire naked body was appear more calm down yet still retained his ferocity before like the Calm before the storm.

[ A/N: Please suggest the power he'll gain. Maybe clone? Not sure, just give me some ideas. It can be a power from other series. ]