Origin

This fanfiction is the ideas of 'What if Tanjiro learned Sun Breathing a lot sooner' & 'What if the fire/water/wind/all of the breathing effects were real' combined into one. It's also gonna have stronger demons and Hashiras. I thought of the idea of Tanjiro throwing around long-range flaming slashes so I wrote it.

This story is similar to my 'Butterfly Effect: Yuta Okkotsu' story in that I don't know how people will like it or how I will be able to have a consistent release schedule for this story. If people like it a lot, I'll figure something out to have it uploaded regularly but if not, I'll just upload it a bit more sporadically. 

Gimme power stones cause the number going up makes my brain feel good. Still don't know what they are though.

...

Deep in the heart of 'Mount Kumotori', a man could be seen performing a ritualistic dance with flames coming off of the staff he danced with.

Off to the side, a woman in her thirties with black hair and dark purple eyes was crouched down behind a small boy of about five years old with dark burgundy hair, matching eyes, and a flame-like scar on the upper left side of his forehead, who was watching the dancing man in awe.

"Do you see, Tanjiro?" The woman who was named Kie asked her son who looked over at her. She smiled down at him before looking back at the dancing man, getting Tanjiro to do the same.

"This is your father's 'Dance of The Fire God' where he offers this dance of flames to the god of fire. This is to ward off injuries and catastrophes in our family because we work with fire." The mother explained getting the child's look of awe to intensify.

Once his father had finished his dance and was properly rested, Tanjiro asked his father how he was able to dance for so long even though he was very sick.

"There is a special way of breathing." His father told him.

"A way to breathe that no matter how much you move, you won't get tired. If you can learn this way of breathing, you can dance forever." Tanjuro said with a hand on his son's head. He leaned over and grabbed a small chest that was hidden behind his bed.

Tanjiro watched with amazement as his father opened the chest to reveal a very old, worn notebook with the words 'Dance of The Fire God' written on it.

His father took the notebook out slowly and put the chest on the ground. Tanjuro handed it to his son, who took it with the utmost care, which made Tanjuro softly smile at him.

"What is this book, Father?" Tanjiro asked while slowly opening up the notebook to the first page, seeing a page titled 'Total Concentration Breathing'. Tanjuro kept his soft smile as he explained.

"This notebook will teach you how to perform the 'Dance of The Fire God' as well as make you strong enough to protect our family." The father said, getting a worried look from his son. His smile became wider when he saw his son's eyes look at his chest before looking back up.

"Can you see it, Tanjiro?" He asked his son, getting a confused head tilt in return. Tanjuro clarified his question.

"Can you see my lungs?" He asked getting a surprised look from his son. When he smiled encouragingly, Tanjiro nodded.

"I can only do it for a minute or two at most, but yeah, I can see your lungs. I can see the baby growing in Mother's stomach." Tanjiro said getting a nod from his father.

"You are quite gifted, Tanjiro. I was unable to access the 'Transparent World' until I was around fifteen or sixteen." Tanjuro praised his son, who looked down with an embarrassed blush on his face before he looked up with confusion on his face.

"What is this 'Transparent World' you mentioned?" Tanjiro asked getting another nod and smile from his father.

"It's the world you are looking into when you look at my lungs or the baby in your mother's stomach." He explained simply, getting a nod from Tanjiro before he pouted.

"I can't use it for long though…" He trailed off before he felt a hand on his head. He looked back up at his father.

"Just do what is in that notebook. Everything will fall into place if you can perfect what is in there. Trust me, I know because I did it even with my frail body. You will far surpass me, Tanjiro." The man said with certainty, making Tanjiro look at him with doubt. His father just laughed softly while rubbing his head before taking his hand off his head and pointing towards the katana in a black sheath with white wrapping on the hilt.

"Once you become strong enough, make sure you always have that sword with you. You'll never know when you'll need it."

.

.

It has been eight years since that conversation with his father and Tanjiro has started training in the 'Dance of The Fire God' and he has made lots of progress.

Tanjiro is now thirteen years old, now being the man of the Kamado household after his father passed away a year ago. He let his hair grow long and tied it into a ponytail like his father's hair.

He can perform all twelve forms of 'Dance of The Fire God', but he can only use the thirteenth form, which is using all twelve forms continuously over and over again, for about an hour.

Tanjiro has been using 'Total Concentration: Constant', which is where you perform 'Total Concentration Breathing' all day and night, for about five years now.

He has also figured out how to smell the 'Opening Thread', which helps guide his blade to the opponent's opening purely using smell.

Tanjiro can also see into what his father called the 'Transparent World', which is an ocular ability that allows him to see someone's muscle and blood movements as well as their breathing. He can access the 'Transparent World' for about two hours before exhausting himself.

Tanjiro is sure there are more uses of this ability, like this 'Selfless State' thing or the 'Red Blade' thing the notebook talks about, and other stuff, but that's the future Tanjiro's problem!

As of right now? Tanjiro is rushing back up the mountain to his home before sunrise. He was at the town at the bottom of the mountain selling charcoal like her normally does when someone insisted he stay with him for the night as it was already dark.

"There are dangerous demons out at night," Tanjiro remembers the man saying over and over again. He tried to say that he didn't need to worry about that and that he could protect himself, but he ended up staying the night so the man wouldn't worry about him.

Tanjiro snuck out before sunrise so he wouldn't intrude any more than he already did in the man's home, of course not before leaving the man a small gift of some of the money he made the day before selling charcoal.

Now, Tanjiro was getting close to where his family's house was when he smelled blood. He thought for a second that some animal had gone hunting nearby, but that thought was discarded as the smell kept getting worse the closer he got to his home.

Tanjiro hears the sound of growling and the smell of blood gets thicker, so he drops his empty basket he used to carry charcoal and unsheathed his black katana that he always kept with him.

*HISSSSS*

Tanjiro took a deep breath that let out a hissing noise as he grabbed his katana his both hands and ran as fast as he could.

*BOOOM*

Tanjiro left a crater in the snow as he shot forward, weaving through the trees.

As his family's house comes into sight, he has to force back the tears when he sees his mother's body hunched over Takeo and Shigeru's bodies. He looked into the door and felt anger course through his entire body.

He could see Nezuko, whose scent had changed almost entirely, crouching protectively over Hanako and Rokuta's bodies. It took Tanjiro a second to realize the growling he heard was coming from her.

In front of Nezuko, was a tall man with unnaturally pale skin, curly black hair, and plum-red eyes. He was wearing a white fedora and a black tuxedo.

The man was unnervingly looking at Nezuko until he got here, more accurately would be to say he was 'inspecting' her.

When Tanjiro arrived and the man turned to see the newcomer, his pupils dilated and he threw his right arm forward.

"Black Blood Brambles!!!"

When he did so, his blood shot out of his arm and solidified into thorny, thin tendrils that were launched in Tanjiro's direction.

*HISSSS*

Tanjiro took another deep breath that let out a hissing sound and entered the 'Transparent World' as he assumed a high stance, noticing with horror that he forcefully ignored how the man had seven hearts and five brains.

He noticed the thorny, thin tendrils that were attacking him from all sides, seemed slow.

Flames shot out of Tanjiro's katana as he swung it in a circular motion in front of him to defend himself from the attack.

"Dance of The Fire God: 4th Form: Burning Bones, Summer Sun!!!"

*SHNK* *HISSSS*

Tanjiro's attack cut straight through the tendrils, letting out a hissing sound as the flames burned through them. The man scowled at the burning feeling.

'This child isn't like that monster, but he could someday become him. I have to eliminate him.' The man thought to himself.

The man drastically elongated both of his arms, growing spiky red or white coverings around his extended limbs and shapeshifting his hands into bladed protrusions.

He swung his arms like whips towards Tanjiro who had his katana held at his right side.

"Dance of The Fire God: 3rd Form: Raging Sun!!!"

He swung it out to the left, then back to the right, deflecting both whip-like arms before charging at the man with flames still flowing out of his sword.

Tanjiro was caught off guard, however, when a third whip-like appendage suddenly came out of the man's thigh, cutting straight threw his neck.

The man scoffed before he narrowed his eyes at the body that didn't bleed or fall. His eyes widened when the body disappeared in an afterimage.

"Dance of The Fire God: 11th Form: Fake Rainbow!!!"

The man heard from behind him as he sprouted eyes on his back to see the child upside down, swinging his katana upwards at him.

"Dance of The Fire God: 10th Form: Fire Wheel!!!"

*TING*

The flaming blade was deflected by another whip-like appendage that came out of the man's back.

Tanjiro turned himself upright in the air and landed on his feet, sliding back about five meters from the man.

Well, if you could call someone who can turn their limbs into sharp whips as well as sprout them from anywhere a man, or even a human.

Tanjiro saw as the man scowled at him as he retracted his whips. The man's scowl got deeper when he looked up to the sky and noticed the sun was going to rise soon.

"What's your name, child?" Tanjiro heard the man ask him, which infuriated him to his core.

This man just killed his entire family except for his sister who he turned into something like himself. Someone who just committed that act of atrocity at most twenty minutes ago dares to ask for his name so casually?

Tanjiro grits his teeth so hard he thinks he cracked them. He had a vice-grip on his katana, which unknown to him, turned bright red for a second near the tip of the blade before going back to black.

"My name Tanjiro Kamado. Who are you? Are you the one who killed my family? Are you a demon?" He asked, glaring at the man while remembering what the man he stayed with last night told him. The man scoffed in response to his questions.

"I killed your family because they are pests, I will do the same to you. It's too bad the sun has saved you this time." The man said before he looked up and to the right.

"Nakime."

*BWNG*

The man called out and the next second, a biwa sounded off and a tatami sliding door appeared next to the man. Tanjiro grits his teeth at the sight.

The man took a step towards the door before glancing at the child over his shoulder.

"My name is Muzan Kibutsuji, and I will ensure your death before you become anything like that monster." The now-named Muzan said before he turned back towards the door to walk threw it. Tanjiro took that as his chance as he took a deep breath and charged.

*BOOM*

*HISSSSS*

Tanjiro left a crater in his wake as he shot towards the man who killed his family.

"Dance of The Fire God: 8th Form…"

Tanjiro pointed the tip of his black katana, which unknown to Tanjiro had become a burning red, at the largest main artery he could see, which just so happened to be the brain in Muzan's head.

"SUNFLOWER THRUST!!!"

*SHNK* *FWOOOOM*

The blade went straight threw the back of the Demon King's head and coming out his forehead, flames burst from the blade and through Muzan's head.

The red tip of the blade combined with the flames on the blade had destroyed the brain in Muzan's head as soon as it touched it, leaving it completely unable to be regenerated.

Another whip-like appendage suddenly grew out of Muzan's right shoulder and cut Tanjiro, who was able to pull his katana out, but still got a light cut from his right shoulder to his left hip that sent him flying.

*BWNG*

Muzan was grabbed by countless hands within the tatami sliding door before the biwa sounded again as the door slammed shut and disappeared.

Tanjiro came sprinting into the clearing a second later with flames shooting off his sword. He paused and looked around when he saw nothing.

Tanjiro wordlessly lowered his katana before looking at the sky and taking a deep breath. He knew he probably couldn't hear him, but he still had to say it.

"I WILL KILL YOU NO MATTER WHAT, MUZAN KIBUTSUJI!!! I PROMISE THE LAST THING YOU EVER SEE WILL BE MY BLADE!!!!!"

Tanjiro panted for a couple of minutes before sheathing his katana and groaning, grabbing the cut across his chest.

'It's hurting a lot more than before and it's turning purple.' Tanjiro thought to himself as he closed his eyes to focus on the wound and calm his breathing.

Once Tanjiro sensed the ruptured blood vessel, he used his breathing to coagulate his blood, stopping both the active bleeding as well as the spread of the poison in his blood.

Tanjiro took another couple of minutes to calm down and process what happened before he suddenly shot up.

"Nezuko!!"

Tanjiro remembered that his sister was still alive, sort of alive, and sprinted back into what was left of his family's home.

When he got in there, Tanjiro saw his sister with fangs, claws, pale skin, and red eyes, still crouched protectively over Hanako and Rokuta's bodies. She was glaring and growling at him as soon as he came in the door. The sight made Tanjiro tear up as he slowly walked towards her.

"I'm sorry, Nezuko… I'm sorry I came home late… I'm sorry for being such a bad big brother… I'm sorry I couldn't protect everyone like I promised I would… I'm sorry you turned into a demon because of me!!!" Tanjiro's tears were flowing by the end as he fell onto his knees a meter in front. of his sister.

Nezuko had stopped growling and started looking at him with some recognition in her eyes as he spoke before breaking into tears as her older brother fell to her knees.

Tanjiro froze as his teary-eyed sister rushed him and hugged him. He took a few seconds to process what was happening before the floodgates opened and he hugged Nezuko back fiercely.

"I'm sorry, Nezuko!! I'm sorry I wasn't here to protect everyone!! I promise I'll turn you back to normal!! Thank you for being alive!!" Tanjiro screamed out as he hugged his sister tightly and he cried his eyes out, which she was also doing.

The two siblings ended up, falling asleep in each other's arms out of exhaustion from what they just experienced.

.

.

Inside a room that seemed to be endless with countless sliding tatami doors, Muzan Kibutsuji was hunched over with his hands on his knees and sweat pouring off of his face.

He had already sent away Nakime as soon as he got through the door, not wanting anyone to see him like this, demon or not.

"It was only a little bit, but I felt that horrible burn I've only felt once before." The Demon King said to himself as he tried to get his shivering to stop. He kept getting flashes of that night.

He saw the outline of a man with hair similar to Tanjiro's hair as well as a flame-like mark on his forehead similar to Tanjiro's mark on his forehead.

"What is the value of a life to you?"

"SHUT UP!!"

*BOOOM!!*

Muzan shot out his 'Black Blood Brambles', destroying the wall in front of him and waking himself up from his daze.

He glared at the broken wall as it automatically fixed itself before clicking his tongue in irritation.

*Tsk*

He snapped his fingers and used his 'Telepathy' to contact the perfect demon to take care of this nuisance.

Two demons appeared kneeling in front of him, one man with a stocky build, pale skin, and black vein-like patterns covering his body, wearing a dark cyan karate gi.

The other had pale, grayish-white skin, with what appeared to be three large, cross-shaped scars cut into his cheeks and the center of his forehead and noticeably elf-like, pointed ears. He was wearing a dotted bamboo-colored yukata.

"Rokuro, Wakuraba, I need you two to find and kill this swordsman with long, dark red hair, wearing Hanafuda earrings with a black-colored katana with a bandaged hilt" Muzan explained as he transmitted the image of Tanjiro to the two demons, who bowed they heads further to the ground in response.

Muzan suddenly grabbed the two demons by the head, transferring some of his 'Demonic Blood' into the two kneeling in front of him, causing the two to fall to the ground face-first.

"You 'Lower Moons' have been useless the last few hundred years. Go do something useful." Muzan said as he lazily waved his hand in their direction, not looking at them once during the entire interaction.

Muzan left the two on the floor to struggle to survive as he thought about what he just experienced.

'Those two won't be enough to kill the child, so I'll send HIM there as well so that when the child is fatigued from fighting those two, HE can kill him.' Muzan thought to himself as he used his 'Biokinesis' to change his body into a child's with clothes to match.

*BWNG*

Another sliding tatami door appeared in front of him he kept walking deep in thought as the door opened to show a small library.

'Even if those two are weaklings, they are still 'Lower Moons 2 & 3'. They will give me valuable information on the child's strength on the off chance HE fails, but I can't see that happening.' He thought to himself as he sat down at the table in the middle of the room and opened the book.

Just after he did so, a middle-aged woman opened the door to the room, peaking her head into the room with a smile.

"Dinner is almost ready, dear." The woman said gently, getting a soft smile from Muzan as he slowly closed the book and looked over.

"Thank you, Mother."