This kimetsu no yaiba fanfiction will be different from the manga. Tanjiro learn breath of the sun from his father from the start of the series. Nezuko will be the same but stronger and the story line will be alter but still follow the main story line. Enjoy.

Chapter 1 Cruelty

(Tanjiro's POV)

How did this happen!?! I just come back from the town down the hill and see all my family are murdered!

One day ago...

'Tanjiro! Come here' my mother said.

She continue saying, 'Your face is pitch black. You don't have to go. It's snowing and it's very dangerous.'

I reply to her, 'I want us to have a great new year's feast, so I'll go sell as much coal as I can. Even if it's just a little. Don't worry about me kaa-san, I learn some breathing technique from tou-san before he pass away. It keep my body warm and I can keep going forever.'

She say, 'Thank you.' with a gentle voice. Suddenly my sibilings run toward me and My youngest brother says, 'Tanjiro! Are you going to town today?'

My youngest sister also says, 'I want to go too!'

My kaa-san says, 'No you guys can't go. You can't walk as fast as Tanjiro.'

They say, 'but kaa-san!'

She says, 'No mean no. He isn't talking the cart today, so he can't pull you when you are tired.'

I say to my eldest younger brother Takeo, 'Takeo, I know you can't do a lot but can you cut a little wood today, okay?'

He replies, 'I will but I was hoping we'd do it together.' I begin to set off and all my family wish for me to be safe, 'Be careful! Hurry back ok!' I wave my hand to them and walk down the hill. Before I could walk down, I meet my sister Nezuko. She greeted me, 'Tanjiro!'

I greet her back, 'Nezuko!'

She says, 'I was putting Rokuta to sleep but I heard all the commotion. They've been so lonely since tou-san died so they've stared clinging to you. See you later!' I smile at her and start to walk down the hill. Our life isn't easy but we're happy. But life is like the weather. Its always changing. It won't be easy and the snow won't always keep falling. When happiness ends, there's always the smell of blood in the air. When I arrived at the town I was greeted by the folks there, 'Oh, Tanjiro! You came down the mountain on a day like today? You work so hard!'

Some other folk says, 'Thanks for fixing my shouji door the other day! Hey sell me some coal!'

Suddenly one of the folk's son run toward me and show me a broken plate, 'Aaah!Tanjiro! You're just in time! Help me! Smell it! She says I broke the dish!' I smell the dish and sense that is a cat smell and I say, 'I smell a cat.'

His mother says, 'A cat? Oh dear.'

He says, 'Seee! I told you it wasn't me!'

There is also another folk says, 'Tanjiro! Will you help me to carry some bundles?!' After I finish helping the folk. I wave goodbye to tje folks in the town and walk back up the mountain. While I was walking, I think to myself, 'Whew! It's getting late!' Suddenly I heard a voice behind me, 'Hey! Tanjiro! You aren't going back up the mountain are you!?' I turn around and see old men Saburo calling me. He continue saying, 'It's too dangerous!'

I reply, 'I've a good nose for trouble. I'll be fine.

He says, 'You can stay here. Please. It's alright you are welcome here.'

I say, 'But I'll be fine. I can walk up the mountain without being tired. I use some special breathing technique...'

He says, 'You don't want to run into any demons,' with a serious face. I have no choice but to stay in his house for a night. He prepare dinner for me and explains to me about demons, 'For ages, man-eating demons have roamed these woods after dark. So you shouldn't walk around at night. Eat, then sleep. You can get up and go home early tomorrow.'

I reply, 'But can't the demons come inside houses?'

He answers, 'Yes. They can.'

I ask, 'Then why don't they eat everyone?'

He says, 'Because demon slayers cut them down for ages.' When I finished listening, I drifted to sleep while thinking, 'Old man Saburo lives alone because he lost his family. He must be lonely. Next time, I'll bring my little brothers. There's no need to fear. There's no such thing as demons but now I think of it, my oba-san said the same things before she died.'

The next morning...

I woke up and begin to set off back home. I waved goodbye to old man Saburo before I leave. When happiness ends, there's always the smell of blood in the air. When I arrived home I drop my basket and I freezed in shock. I saw Nezuko laying on the snow cover in a pool of blood while hugging Rokuta. I quickly went up to them, 'What the...? AGH! What happened?! What hap-' I widen my eyes in disbelief when I saw all my family was killed. I almost break down in tears but suddenly I felt Nezuko weak pulse. I quickly carry her down the moutain to seek a doctor. While I was walking, I rethink the tragic event, 'Only Nezuko's body was still warm. Maybe a doctor can save her. How did this happen? A bear? Maybe a bear too hungry to hibernate? Keep going! Move your feet faster. Use the breathing techniques that tou-san taught me. It's still a long way to town. I won't let you die. I have to save you. Your onii-chan will save you!' Suddenly I felt movement at my back. I turn my head around and see Nezuko raise her back. She suddenly let out a grar. She thrashes around a bit and make me slip. We fall down a short cliff. I landed on my back but the snow cushion my landing. I quickly sit up and call her name, 'Nezuko!!!' I looked around my surroundings and notice Nezuko is standing up.

I quickly went over to her and say, 'Nezuko! Are you alright? You shouldn't be up! Let me carry you into town!' I grab her shoulder and suddenly she look up. I was shocked to see her feature had changed. Her black hair fades to orange near the bottom. Her eyes are bright pink with slitted pupils. She suddenly grab me with a strong grip and launched toward me. I quickly grab my axe from my axe sheat and put the axe handle in her mouth. She kept biting the handle and won't budge a inch. I keep resisting her, it was like she want to bite me.

I though of old man Saburo said, 'A demon! No that's impossible. Nezuko has been a human since the day she was born but this Nezuko smells of blood and death. But Nezuko couldn't have done all that. I found her fallen over Rokuta, like she was protecting him. She didn't have any blood on her mouth or hands. And there's yet another smell.' Suddenly she grows bigger. She's getting stronger. I use a breathing technique to increase my strength and resist her. While I was safely asleep in town something horrible happened to my whole family. How they must suffered and I wasn't there to help them. I have to safe Nezuko if I can!

I shouted at her, 'Hold on, Nezuko! Fight it! Fight for your life! Be strong! Don't turn to a demon! You can do it!' while looking at her with my teary eyes. She look into my eyes and started to calm down. She starts to cry and I felt relieve that she is calm. Suddenly I saw a man holding a katana appear behind Nezuko. He gonna slice her! I breath in air and make my blood flow faster. I quickly hold Nezuko and jump a great distant. The man was shocked to see me jump that far.

I think, 'Who is that? He's holding a katana.'

The man says, 'Why do you protect her?' with a expressionless face.

I say, 'S-sister. She's my little sister!' He look at me with a confused expression and suddenly Nezuko thrashes around wildly while letting out a grar.

He responds, 'That is your little sister?' He quickly dash toward us and I pull Nezuko down with me to protect her from him. When I am down, I noticed Nezuko is gone. I look up and saw she is capture by the man. She keep thrashing wildly but failed to escape the man's grip. I shout her name, 'Nezuko!!!' while standing up quickly.

He says, 'Don't move.'

I stop and say panicky, 'Wait! Nezuko hasn't killed anyone!'

He responds, 'Killing demons is my job. Of course I'll take your little sister's head too.'

I say, 'There was a scent at my house... from someone I've never smelled before. That must be who killed everyone. Not Nezuko! I don't know what's making her act like this but...'

He reply, 'That's easy. Demon blood got in her wound, so she's transformed into a demon. That's is how man-eating demons multiply.'

I quickly counter him, 'Nezuko would never eat anyone!'

He responds, 'A moment ago she almost ate you!'

I say, 'No! I'm sure she knows who I am! I won't let her hurt anyone! I'll find a way to cure her! I'll make her human again!'

He says, 'She won't get better. A human who becomes a demon cannot go back.'

I reply, 'I'll find a way! I swear! Please don't kill her! I also find the one that killed my family. I'll do all that, so...so...' with a teary voice. He raise his katana and gonna cut her head.

I shout at him, 'STOP!!!!' I can't lose Nezuko too. I quickly grab my axe and rush at him to cut him down but he kick me. I was pushed back several feet but I am still standing. I calm down for a while and rethink my tou-san's teachings, 'Tanjiro. Always stay calm while facing an enemy. Use the breathing techniques that I taught you to defend yourself and your family.' I harden my eyes and take in a deep breath. I let out a hiss sound and rush toward him in a burst of speed. I hold my axe with two hand and yell, 'Total concentration. Sun breathing! First form Sun Waltz!' My axe was set ablaze and I slash him. He quickly blocks my axe with his katana but I cut through his katana. His katana was cut in half. With a fast movement I quickly grab Nezuko and hold her in a bridal carry. I leap further than last time and land safely onto the snow. I turn around facing him while holding my axe. I stared at him with my calm eyes while holding my position. I say to him, 'If you come closer to my sister again. I will cut you down!'

(Giyu's POV)

What the! How can he use breath style? He is not trained by the pillar yet he cut my blade with a rusty axe. He might be as strong as a pillar. His demeanor suddenly change from panic to calm. Probably one of his family is a demon slayer. I also notice that demon was hugging her brother from behind. She did not eat him. I also never heard of that breath style before. I look at them and think for a while. This is my first time seeing a demon not attacking human. These sibilings might be special. They might stop the man and end all demons's existence. I say to them, 'I won't kill your sister. Go see an old man names Sakonji Urokodaki who lives at the foot of Mount Sagiri. Tell him that Giyu Tomioka sent you. He will make you a full fledge demon slayer. Your sister should be fine because the sun isn't out today but don't let her into direct sunlight.' After that, I toss a bamboo mouth guard to him, 'Use this to put on her mouth.' I quickly leave them be.

(Tanjiro's POV)

Whew, he left. I grab the mouth guard and put on Nezuko's mouth. Me and Nezuko quickly went back home and bury all my family corpses. I pray for them to be fine in heaven. I grab my sister hand and lead her down mountain to search for the old man that Giyu mentioned while looking back at my family grave with a sad face. My road gonna be very hard to walk but as long as I have Nezuko, I can overcome any obstacles.

End

The next chapter will be release in a few weeks so just wait. Leave a comment and Jane!