Y/n P.o.v.

Shinobu: "My name is Shinobu Kocho, and this is Kanao Tsuyuri. I believe that you are here for the internship." I just nodded, still with my jaw dropped from just seeing the two girls from Kimetsu no Yaiba. Specially Kanao, which she caught my eyes when I saw her in the anime.

Y/n: "I-I-It's a p-p-pleasure to m-meet you b-both!" I was a stuttering mess. "I-I'm Y-Y-Y/n L-L-L-L/n." Shinobu giggled while Kanao made the gestured.

Shinobu: "I believe that I said your name moments ago." My face went super warm and I looked away because of embarrassement. "Furthermore, may I see your outfit?" I nodded and gave her the suitcase.

She took it and gave it to Kanao. Once Kanao took it, she opened it to inspect it. Kanao shook her head in disappointment and showed it to Shinobu.

Shinobu: "Oh my." She had the same smile, but that phrase sounded like it was in disappoinment. "This isn't good."

Y/n: "W-What's wrong?" She turned to me.

Shinobu: "This outfit has poor design. If you wish to train with me and learn the ways of our sacred ways, you must wear appropriate clothes. Fortunatelly, we have made an appropriate robe for you to use." I scratched the back of my head.

Y/n: "Well, that costume was actually given to me. It's not like I had the choice of making my own costume. But, it actually suited my need for the time being."

Shinobu: "Well, then we'll have to make further adjustments to your hero costume for the future. For now, we must head to our place." Kanao closed the suitcase. "Just in case, you won't have signal once we've reached our place. So, I suggest for you to call someone before we leave." I nodded while taking out my phone.

I searched for my contacts and the first person was Jiro. 'Why not?' I tapped on the phone on her contact, and it started dialing. I put it on my ear and I heard it ringing. Few more rings, and then she answered.

Jiro: 'Y/n, it's some sort of a bad time for calling.' *EARPHONE JACK, HURRY UP! I HAVE TO BRIEF YOU FOR YOUR TIME HERE!* I heard Death Arms from the distance.

Y/n: "I'm sorry, but I had to tell you before I head into my intership as well. I won't have any signal until the end of the internship. So, I decided to let you know before you get worried that I haven't answered your call or texted."

Jiro: 'Oh, ok. Thanks for the heads up. Good luck in your internship.'

Y/n: "You too. And, by the way, want to talk about that last kiss you gave me before we parted?" She hung up. I looked at my phone with a smile. 'Guess that's a no.' I thought.

Jiro P.o.v

'I WISH I COULD MAKE MY JACK GO THROUGH THE PHONE AND TOUCH Y/N FOR REMINDING ME OF THAT!' I thought in embarrassement. My face was heating up by the second.

Death Arms: "Earphone Jack, are you done talking to your boyfriend!?" I turned to him with wide eyes and my face was heating up even more.

Jiro: "I-It wasn't m-my boyfriend! Y-Y/n and I d-don't have that s-sort of t-thing yet!" His eyebrow raised.

Death Arms: "'Yet'?" He had a small grin. 'Oh crap, what did I say?' I thought in embarrassement. "So you're planning to be? And with that Y/n fellow? You have good taste."

Jiro: "C-CAN WE C-CONTINUE WITH THE B-BRIEFING!?"

============Timeskip============

Y/n P.o.v

After I called Jiro, Shinobu insisted for me to start heading up the mountain. I wanted to call Momo and Ashido, but she wouldn't let me. Anyways, Mt. Fuji wasn't really our destination. It was another mountain nearby that was secluded from tourists and closed for them.

During our walk told me all about the breathing styles. That they all were derived from the Breath of the Sun, the first made technique. The others were created by other users. Now, they were 14 Breathing Styles, but with the Dance of the Fire God was unknown to how it was created. Shinobu thought that it was a related to the Breath of the Sun, since one of the pillars mentioned it once.

Shinobu: "Now, before we begin, how long can you run?"

Y/n: "100km."

Shinobu: "Push-ups and sit-ups."

Y/n: "100."

Shinobu: "My, you really like to be in shape."

Y/n: "Ever since I learned that this abilities requires a lot of breathing and a lot of enduracne, I wanted to create that sort of resistance."

Shinobu: "You thought well. But now, will be a test to that endurance and make it stronger." I gulped the saliva that I accumulated without me knowing.

We've reached our destination and it was a shrine. The japanese gate at the top of the hill, three houses which were two on the side and one in the middle making a 'U' form, and path to the right that was between the houses. 'This is way different than the one from the anime.' I thought, realizing that this was a different place.

In the middle was a small flower like fountain with water sipping out from the middle. 'This place is really pretty and well hidden. How does that water get to here?' I asked myself.

In front of the fountain, stood four other girls. I recognized them, but I don't remember their names.

One of the girls was a little taller than the other three, she had blue eyes, blue attire, and twintail hair with blue butterflies as their support. She kept her tsundere stare at me.

The other three girl were almost like triplets. One had blue butterfly wings, one had red butterfly wings, and the last one had green butterfly wings. Each of them had different hairstyles, and yet, they looked like triplets. They were holding something wrapped.

Shinobu: "Welcome to the Butterfly Estate. Here, you will train with Kanao and myself to develop you Breathing Technique. You will learn how to constantly use it." She pointed at the tsundere. "That one is called Aoi Kanzaki, she will be your cheerleader from now on." I walked toward her and offered my hand with a smile.

Y/n: "It's a pleasure to meet you. My name is Y/n L/n." She looked at my hand  with suspicion, but she shook it without saying another word.

Shinobu: "This other three little mistress, are Sumi Nakahara..." I patted the blue butterfly girl's head. "...this one is Kiyo Terauichi..." I patted the red butterfly girl's head as well. "...and this one is Naho Takada." I patter the green butterfly girl's head. 'This girls will also be supporting you during your stay and training."

Y/n: "It's a pleasure to meet you all." I bowed my head and stood up straight.

Sumi: "We're glad to finally meet you!"

Kiyo: "We've made something for you!"

Naho: "We hope that it suits you!"

The three of them offered me the wrapped object. It seemed that it was some sort of cloth. I took it and thanked them. Once I unwrapped it, I actually liked it.

The colors really looked pretty, despite being black and white, and the details on the dragon hovering over the mountains and water was really eye catching.

Aoi: "Can you put it on already!? It's not really that big of a thing."

Y/n: "I actually like it. It's really pretty and the details are so..." I thought for a word, but non came. "There aren't words to describe how awesome this design is." I looked at Aoi and she looked away with a small tint on her cheeks.

Shinobu: "She's actually glad to hear that, since she's the one who made the design."

Aoi: "Sh-Shinobu!"

Sumi: "She used your Breath of the Water as reference for the ocean."

Kiyo: "She used your Breath of the Thunder as reference for the sky."

Naho: "And she used your Dance of the Fire God as reference for the dragon." I looked at Aoi and her cheeks were puffed and her face was about to explode from so much redness.

Y/n: "It's an honor to have this from you. Thank you." I bowed my head and she was loss of words and I saw steam coming out from her head. Shinobu clapped.

Shinobu: "Alright! Time to start to train! Change into your outfit and meet me at the top of the mountain." With that she jumped toward the top of the mountain with Kanao following her.

I gulped, knowing that this is where I might be dead before I come down that mountain.

============Timeskip============

I've reached the top, almost the top, where Shinobu and Kanao were waiting for me to arrive. I was wearing my hero outfit, but instead of using the leather coat, I was using the gift that they made me.

Shinobu: "This outfit suit you better." I scratched my cheek in embarrassement and I was having a little problem with breathing at the moment. "Do you feel it? That you can't almost breath?" I nodded. "Good. It seems that the beginning of your training starts here." She, alongside Kanao, sat down while folding their legs.

Y/n: "What would you have me do?"

Shinobu: "Run." I tilted my head in confusion. "I want you to run around. See that path?" She pointed to her side. There was a path. "That path leads to this end." I turned to the other side of her and saw that there was another path. "Now, I want you to start running with the dense air that you feel. Be warned, that once you start, there will be many obstacles for you to evade, so tread lightly. I may also add, that once you're done, there will be new obstacles for you."

Y/n: "Alright. Then, I'll start now." I stretched my legs for warm up. I saw Shinobu nodding to Kanao. Then, Kanao looked at me with her smile.

Kanao: "I suggest for you to use the breathing technique. It will help you for your training for Constant Breathing Technique." I nodded with a small smile to finally experience Kanao to talk to me.

I used the breathing technique, I felt stonger on my legs, and my lungs expanded. Then, I started running.

============Timeskip============

I finally, FINALLY, reached Kanao and Shinobu right at the start, and I fell face first to the ground while panting, with cuts on my arms, legs, body, and face, burn marks, and some bruises.

First things first, I took off the kimono and wrapped it around my waist so it couldn't get that damaged. Because it was too nice for it to be destroyed.

Secondly, this obstacles were hell! Hidden logs ready to hit you, arrows ready to hit you, fire arrows, hallow floors, boulders falling from the top of the mountain, spikes, piranhas. FREAKING PIRANHAS!!! Where in the heck will someone find piranhas in Japan!?

And thirdly, I can't breath. This dense air really was something. I managed to dodge a few obstacles while doing the techniques, but I couldn't do it because of how dense the air was. 'This training will be the death of me.' I thought. 'I want my bed.' I flipped and was met with Shinobu looking down at me with tilted head.

Shinobu: "How are you hanging there?"

Y/n: "Out of breath. This training really is something else."

Shinobu: "Is that a good thing or a bad thing?"

Y/n: "Bit of both." Her smile grew.

Shinobu: "Good to hear." She sat beside me and made my head lay on her lap. I was too tired to think about the situation. "Rest for a bit. And then, you may continue." I sighed while calming my mind and resting. "Let me explain what will happen with the rest of your training."

Y/n: "Is there more to this?" She nodded.

Shinobu: "There are three phases that you must succeed within this week. And I know that you'll make it." I nodded for her to continue.

================================

A/n: Welp, seems like the training is going to be tough like it happen to the trio of Demon Slayer.

Anyways, as usual, hope you liked it, vote and comment for the chapter and stay tuned for next chapter.

Stay cool people,

Drako Auditore Out!!!