Hello everyone and thank you for reading my fic. I know its not original but I've had an idea of writing a story of Izuku as a swordsman with skills of the Demon Slayers. He will have an elemental quirk so that he can actually make the effects from the breathing styles. I also plan on doing a fic where Izuku is quirkless and uses total concentration breathing to keep up with others who have quirks. Please read and review, I am new to this. Thank you all!

DISCLAIMER: MY HERO ACADEMIA AND DEMON SLAYER BELONG TO THEIR RESPECTIVE CREATORS. I DO NOT OWN THEM.

Chapter 1: What it Takes!

The world was a strange place. Roughly about 80 percent of the population had developed some kind of supernatural ability while the remaining 20 percent were left powerless. As expected, the crime rate went up all around the world with chaos taking over everything. Hope was not lost though because heroes eventually rose up and combated the evil. After many years of battle the hero system was put into place. People with the drive to do good could finally hone their powers and skills to protect the innocent and loved ones. This is the story of one of those heroes.

Izuku sat with his mother on the train ride to the hospital. It was time for his monthly quirk check up. Compared to other children, he was considered a late bloomer. The five year old boy squirmed around in excitement while his mother made sure the time was correct. Izuku was lost in thought, wondering what kind of ability he would have. His mother has a quirk called attraction to small object which is basically weak telekinesis that uses pulling motions to grab said small object. His father while being gone since he could remember has a quirk called fire breath which just allowed him to breathe fire.

Izuku thought of which quirk he might inherit from his parents or if it would be a combination of both. Maybe something that would allow him to control the fire he breathes out? There was also the option of him developing something completely different from his parent's quirks. Despite being so young, Izuku has a nack for quirk analysis and research. It was his luck that the town library is where his mom would pick up extra work shifts, so doing homework and research was easy enough.

Inko Midoriya did what she could to take care of her only son. Sure, things were hard after the disappearance of her husband, but that wouldn't keep her from making sure her baby was well. The last she had heard from him was when he mentioned getting work in the states. that was over three years ago. No matter how hard she looks for his traces there was nothing that came up. The hard part is keeping the truth from Izuku and that brilliant mind of his.

The train ride took quite some time as the Midoriyas lived on the outskirts of the city. Inko and Izuku mostly stared out of the window at the buildings that varied in size and shape.

"What do you think my quirk will be momma?"

Izuku asked, still looking out the window. His mother looked at down at him in surprise. She had wondered the same thing and would be lying if she said she wasn't curious.

"I'm not sure baby, but it will probably be something like mine or your father's."

Izuku nodded expecting that answer. The feeling of excitement causing his little body to shake as if on a sugar rush. Looking down at the All Might toy he brought with him, he decided that he'd grow up to be a strong hero who will save everyone with a smile just like the symbol of peace. Inko watched Izuku from the corner of her eye and smiled to herself. It's scary but also very heart warming go know that your kid wants to be a hero.

The pair finally made it to the hospital with minutes to spare. The greenettes walked up to the front desk and saw a woman wearing a white uniform with a clipboard. Izuku saw her appearance and immediately went into analysis mode. Her skin is a bright pink color and her eyes are black with yellow pupils. To top it off, her hair goes just below her back and is very bushy. She also wore gloves that looked to be made out of some kind of protective material. His brain started forming more questions rather than answers.

'Why is she pink? do her eyes see better than regular eyes? Are those gloves for us or for her?'

"Oh, you two must be the Midoriyas!"

She chirped out happily while the pair approached. Inko nodded and returned the smile.

"Yes, we're here for my son's quirk check up. He's due for one soon."

The other woman nods while typing in their names into the computer. A few seconds go by before she looks back at them.

"Alrighty, little Izuku will be seeing one of our finest doctors. His name is Dr. Tusbasa. He'll be in room 402 on the fourth floor."

Inko nodded and thanked the woman. She took Izuku's hand and went to a near by elevator. While they waited to arrive to the fouth floor Izuku tugged on his mother's hand.

"Do you think I'll be able to be a strong hero with my quirk, mom?"

He asked with an excited smile. Inko looked down at him and gave him a gentle smile. She knew that he'd always wanted to he a hero, but there is always the chance that he'd get a quirk like hers. Something to weak to use to protect someone.

"I'm sure you'll do amazing things Izuku."

The look in his eyes made Inko's heart swell with pride. She's always been happy to have such a kind hearted son. The walk took a little longer than expected but they finally made it to Dr. Tusbasa's room. The greenette mother knocked on the door and made sure Izuku wasn't too close as to not bump into anyone. The door opened after a minute and a short elderly man was on the other side.

"Good evening folks. I'm Dr. Tusbasa, its a pleasure to meet you both."

Izuku waved at the Doctor happily while Inko smiled politley and offered a hand shake. The Doctor took the offer and smiled back generously.

"Hello doctor, I hope everything is well today. This is my son Izuku."

"It's nice to meet you lad. Says here on my schedule that you have a quirk check up today. Those are always exciting!"

Izuku nodded and showed the man his All Might toy.

"Yeah! I'll be a super cool hero like All Might! He always saves people with a smile!"

The doctor let out a hearty laugh and took off the goggles that covered his eyes. He turned around and picked up a clothes to wipe of the lenses.

"That's a big dream kid. You better work harder than anyone else you know. Just make sure to eat your veggies and stay in school."

Izuku nodded without a word. The doctor started to set up an X-ray and some other tools to help find out what Izuku's quirk could be. The first test was to scan his body and see if any mutations have happened that aren't visible on the outside.

"Interesting, yes very interesting."

The doctor said after having a look at Izuku's X-ray sheets. He fliped through different sheets and carefully inspected each one. He looked up at Inko then at Izuku.

"It appears that little Izuku here has some kind of mutation quirk that grants him with lungs larger than what they should be for a child."

He holds up the X-ray for the pair to look at. Izuku's ribs were at a odd shape to fit his lungs, which were obviously bigger than what they should be. To makes things a little clearer, the doctor showed them a recording of Izuku's lungs as he was normally breathing. They appeared to be processing oxygen but pumping at a slow rate.

"Dr. Tusbasa, is this normal for a mutation quirk? My baby could be having health issues already? What happens if he can't breath correctly?"

As Izuku heard his mother bomb the doctor with questions he tilted his head. He didn't have any health issues that he could think of. If anything, he actually had lots of energy. He's noticed that it took a lot longer for him to get tired or exhausted then other kids and most adults at his school. Sure he got tired some days, but it rarley happened. The downside of that is he'll get crazy hungry amd devour anything edible.

"uku... Izuku! Are you listening, son?"

Izuku snapped back to what was happening. He looked at the doctor and his mother. The doctor had a semi impressed look mixed with a bit of a smile. His mother just looked at him with a small smile, use to his antics.

"was I mumbling again?"

He asked with a lil shyness. The doctor and his mother let out a chuckle while he pretended to pout.

End of the check up...

Dr. Tusbasa did a few more tests with Izuku after hearing that he had more energy than the average quirked child. One test confirmed that Izuku's larger lungs did infact grant him more energy with how much more oxygen he was able to inhale and exhale. Something weird happened during one of the reaction tests. Dr. Tusbasa used a small rubber hammer to tap on Izuku's knee and when Izuku's leg kicked out he let out a surprised breath. The moment his leg went up, a small wave of fire followed.

So this is pretty much the introductory chapter. I hope that it went pretty well for a first shot. The idea of Izuku's quirk is that he can create the elements with his breath. He inhales and turns the oxygen/energy into said element he wants to use. I picked fire first cause his father could literally breath fire, lol. Anyway please read and review. Any advice would be lovely.