Cataclysm // Demon Slayer Deku

Understanding

Izuku's POV:

It's been over a week since I first learned about the demons and demon slayers. I've fully recovered and my vision is now back to normal. In that time I've learned so much more than I had previously known. For example, I've learned that the building I recovered in is called the Butterfly Mansion.

It makes sense as to why, with all of the different kinds of butterflies flying around the place. It's apparently the place where demon slayers heal and re-train their bodies after garnering injuries from missions.

I have trained my body a little immediately after I fully recovered. The doctor who had taken care of me would continuously push me past my limits, not letting me rest until I was passed out on the ground.

It was honestly the most grueling thing I've ever done... but the pain was still nothing compared to what Kachaan would do to me on a regular basis. Everyone in the Butterfly Mansion were extremely concerned at my unusually high pain tolerance. But I assured them that it was nothing to worry about.

I'd have to run around the Butterfly Mansion at least 100 times before I was allowed to drink water. I'd have to practice my reflexes and evasion skills with the trainers in the Butterfly Mansion, I'd lose every time, but I felt myself getting better and better each time I did it. I over heard some of the trainers saying that I am too fast of a learner.

I hadn't seen that demon slayer girl who saved me at all, but I did learn that her name was Hina Agatsuma. I heard that she got a massive boost in rank and was busy for several days after her recovery.

Everyone I met was really nice... none of them seemed to care about me being quirkless, mainly because most of them were either quirkless themselves or had very weak quirks that didn't make much of a difference to their lives.

I have been trying to gain a better understanding of my "slow-mo vision". It seemed to be based on concentration... the better concentration I have on a moving object, the slower it appears... so I decided to start enhancing my concentration.

If I really am quirkless, then I shouldn't be able to have this "slow-mo vision". I was always nervous to talk about it with other people... I never even mentioned it to my mom... but maybe if I asked the doctor... she might know something about it, she's really smart.

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I knocked on the door to the doctor's room. I twiddled my thumbs, anxiety creeping through as I waited for an answer. "Hopefully she'll know what this is... she's probably the only one I know who might..."I thought.

The door swung wide open, revealing the doctor who had taken care of me and trained my body for the past week. "Oh, it's just you brat... what do you want?" she asked, seemingly a little annoyed. I gulped, trying to find the right words.

"I-I have a qu-question..." I started. "Ask away," she said. "S-so I-I um... I have this weird thing going on..." I continued. "Sometimes I see things moving slower than they should be..." I stated.

The doctor raised an eyebrow. "Go on," she said. "I-if I concentrate really hard on something that's moving... it looks like it's in slow motion... I've been trying to work on it lately but I'm still not sure what it is..." I explained.

I looked up at the doctor and stared her in the eyes. She was wide-eyes, eyes full of shock and disbelief. I panicked slightly. "D-did I say something wrong?" I questioned. "Kid, are you sure that you're quirkless?" she asked abruptly.

I winced a little at the unexpected question. I only nodded hesitantly, unsure of what she was getting at. "Do your eyes hurt when this happens?" she asked, seriously. Now that I think about... my eyes do sting a little when it happens, but it's not that uncomfortable as I'm used to lingering pains due to Kachaan's beatings.

"They only sting. They don't hurt too much when it happens though," I explained. The doctor's eyes narrowed at my words, but it looked like she was still recovering from some type of shock for whatever reason. "Come in," she ordered, walking back further into her room.

Reluctantly, I stepped into the room, closing the door behind me. I watched as she frantically began searching through a large bookshelf filled with every kind of book you can imagine. "Not here... not this... no, no," I hear the doctor mutter as she flipped through several books quickly.

"Here it is!" she yelled, pulling out a pinkish purple book. I walked over in an attempt to get a closer look at the cover. It did have Japanese kanji on the cover, but the kanji was unfamiliar... almost like it was an ancient version of Japanese.

She moved her hand across the cover, blowing on it slightly, indicating that it was probably a little dusty. Quickly, she flipped through page after page of the strange book, before finally coming to a complete and abrupt stop on what looked to be the final page.

She muttered some words that I couldn't fully hear, but I could tell that her tone wasn't really pleasant. "How is this possible?" she asked, quietly. "I-is something wrong?" I pondered aloud.

She took her eyes off of the book and glared down at me with a slight menacing look on her eyes. "How could a little snot like you know how to uses breathing technique like this? You had no formal training or knowledge of any of this..."

I was confused, not really understanding what the doctor was saying. "Breathing technique?" I asked, a confused tone lacing my voice. "I had heard some of the trainers in the Butterfly Mansion talk about them, but I never got an explanation of what a breathing technique is," I informed the doctor, cautiously, as not to reveal the fact that I regularly eavesdrop on conversations to gain more information.

She only grunted in frustration, the sighed in acceptance. "Breathing styles are forms of swordsmanship techniques. By breathing in certain ways, one can increase certain aspects of the body and gain the ability to more effectively slay demons," the doctor explained in what I could only assume to be simple terms.

This was interesting to me... yet another way that I can become stronger.

"You seemed to have been accidentally using a Flower Breathing technique that enhances the user's vision to such a high degree that they perceive the world as if t were moving in slow motion. This technique is called Equinotical Vermillion Eye,"she stated, handing me the book, allowing me to look at its contents.

"Equinotical Vermillion Eye?" I thought to myself. I couldn't properly read the contents as the kanji weren't modern-day kanji, but I assumed that it basically said what the doctor told me. The only thing that I understood was a drawing of two eyes on the page, depicting what the technique would look like when used.

"Brat, when did you first use this technique? Where did you learn how to use it?" she asked. I snapped out of my awe at the drawing and quickly turned my attention back to her. "I-I was 4 when it first happened... I was protecting this kid from a bully. The bully tried to punch me, but it was moving very slow... so I just stepped out of the way," I explained, handing the book back to her.

She stared blankly at me, searching for something in my eyes. When she seemingly didn't find what she was looking for she grunted in frustration, sighing to let some stress out.

"Be careful when using this technique, kid. If you use it too much or if you use it to a high degree, you may pop the blood vessels in your eyes, the strain on your eyes may even cause you to go blind. If I were you... I wouldn't use it again until you've gotten a better grasp on Breathing Styles and how to use them," she stated bluntly, but with a subtle worried tone.

I whispered at the thought of it, only to nod my head in confirmation. "Now go away. A high-ranking demon slayer would like to start training you tomorrow, so be ready for that... it'll be way worse than the training I put you through," she informed me, shooing me off.

I pouted slightly, only to be overcome with determination a few moments later. I left the room, only one thing on my mind. "I will become stronger for you, mom... I won't give up!"

Author's Note: Yet another exposition-based chapter, but you understand, right? Gotta build up the world before getting into the action.

We've found out just what Deku's slow-mo vision is. As I said in a previous chapter, it is not a quirk, so Deku is still quirkless, it is the final form of Flower Breathing.

Thank you for the support, just yesterday this story had 50 reads, and now its jumped up to 70. I truly appreciate it, and I hope more people will find my story and become interested.