reincarnated in demon slayer

Hari was transmigrated in demon slayer world well he knows that because he got the memory of the body he is now in. The previous bodies owner was servent of the family of Muzan and he was the one caring for him when he was sick. When he got better he was stronger too. He wanted me to become like him and he was the first one Muzan tried to turn he gave too much blood and he was dead. And now I took over. I was not a demon but i can control my age and i have increased regeneration. So i think iam immortal. I looked around and i was under snow by a Cliff. It seems that he just threw me away. now that i am immortal i wanted to be safe. If Muzan knows i am alive and can walk in the sun he will absorb me. So i went to the capital i think i should learn to use a sword then when the demon slayer corps is built and is functioning properly i should join them. I took the form of 5 year old when I reached the capital and asked around. There is only one school I could join that didn't require any money. It was not the best but it tought every thing about a sword and i was struggling to learn i didn't even touched a sword before. 5 years it took me to learn from them. It only teaches them the basics. The other children took only 3 years to learn. And that is including the hour's i put in i didn't need to rest and eat. I sleep only for four hours. But i got the basics right and burned it in to my bones. Now i needed to get some advanced sword techniques i changed my age to 5 again and joined another school the best one. I borrowed money from some drunk people that bothers other at night during these 5 years. Then i joined that school i was taught very well by them for another seven years for me to learn everything they tought. After that i changed my age to suit the other schools teaching fighting styles of various groups and studied them. It always took longer than others children but i was learning faster as i relate other fighting styles with the current ones i am learning. It took 100 years to learn and take what i needed and mold it in to my own fighting style. Then i began to travel Japan fighting and killing bad people. My first kill was one night where a man tried to rape a child i sneaked behind him and split his throat as i coverd his mouth after that i didn't sleep for 2 days but i knew it was necessary. I know I will never get that feeling away but it was needed. That kind of people should be put down. And during these times there are many that are like this. I travelled to where fighting was and joined many clans that are about to fight others and fought with them in wars against other clans i always try to join the ones that have atleast good reputation among the commeners. It was the only way to grow stronger. And i did i always try to breathe like it was shown as demon slayers did but i couldn't get it right for me comfortably. But during the wars it just clicked and i have a breathing technique. It was not anything special. I have hightened performance and contentration. And i am always in total concentration it always hurts my lungs first but due to my healing factor i adapted faster. It also took about 100 years but i can now be called an experienced fighter. I can even kill some lower level demons if i got the weapons for it. But now I decided to travel and add more fighting techniques from all over the world to my style before coming back to Japan. The demons are growing stronger and demon slayer corps are trying to fighting back but it is always on the loosing side but i know about 300 years later a demon slayer will invent breathing techniques and fighting styles for killing them. I still was not strong to fight back and i was not an inventer but I had time and i will create my own style from learning theirs and save as many as i can without killing my self. For 300 years i traved the world and i learned martial arts and killing techniques. I was closer that ever to getting the demon mark. But it has always been one step away from me. Now i have the power of a hashira so i began to go back to Japan. I first took the age of 20 year old and went to look for demon slayers. After week's of searching i found one fighting and loosing to a demon i helped him defeat the demon by distracting and he sliced the demons head. He asked me to join the demon slayer after i told his my family was killed by demons and i trained for long time to fight and kill them. He told me where the test was and he will tell his master to sent a letter to the demon slayer corps. It has been 3 years since i joined the demon slayer corps. I tought them breathing techniques i created and it helped a lot and they taught me the sword forms of fire lightning water earth and air. And i have killed more demons for than anyone here so they have promoted me to hashira. I asked them to find a family man with a surname Tsugikuni and wife named Akeno. He found them a year later they had only been married some week ago that is why he could not find them. He began to slow down his demon hunting and began to teach and perfect his breathing techniques with blade welding forms. He put on the an aged forn stating that his family has people dying in their 30-40 year. 3 years passed and he yoriichi was born he was their when the baby was born. As the father said that the baby was ominous i said that i will keep the baby and gave them a sum of money they could not refuse. It was huge considering that it was a major portion i got from demon hunting job. I pleaded to the wife saying he will be essential to defeating the demon that we cannot. And has been killing and eating family mothers children. I was talking to her alone after convinced the father by giving him the money. She was reluctant but she was religious person and i knew it from the manga i read. I told her i was sent here to train him to kill the master of the demon and her husband would kill the baby because of the mark of God in his face. I begged her to forgive me for making her do this. She agreed i had no choise. This was the best way to kill Muzan i don't know if i can defeat Muzan and even if i tried to change little things the butterfly effect would change so many things. I dont know if tonjiro can defeat him. So i will train the orginal breadth user and this time i will make it so that yoriichi can kill him. Muzan doesn't know i am alive the demon slayer corps thinks i am dying and will die in 10 years. And Muzan definitely doesn't know about yoriichi. I know that Muzan have seven hearts and five brains. He will teach him to kill Muzan so that he will prevent anyone from getting hurt. He began to raise the boy he first when the near by villages and settled in a village where little girl named uta was born. I had brought with me a widow that recently lost her child. I made the demon slayer corps look for the villages for uta as well as caretaker for her milk only because i will be raising him. I told them i will teach everything to a child before I go. I brought a house near parents of uta. After 2 years i sent the care taker away. He already has some strength in him. He doesn't cry or laugh but uta's parents bring her over some times and he will be a little more receptive then. I read to him and teach him words and stories. Everything i know about Muzan. I told him his mother gave me to me and that she sacrificed so you can fullfill your duty. I said i will train you till i cannot teach you anything and he will teach me after he surpasses me. He was always perceptive one. I will regularly show him the breathing techniques and sword forms. I told him how regular people see the world. After that i told him that only he can live more than 25 years old with that mark on his face. Anyone else will die. I told him to teach it only to me because i am special. When he was 5 he already knew every breathing techniques and form. Then i tought him the sun breathing techniques the whole 13 forms it was hard not because of him but me i still had not perfected it but with his help we both learned and perfected the forms when he was 9 i told him for a year we will be going around killing demons and people that kills and do bad things for their pleasure. He and uta was reluctant but i told him we will return soon. For 6 months he killed demons and people too. He held no emotions but i know that he was reluctant to kill people but i shoed him when we show mercy what will happen. We followed the man we let go he was part of bandits and he joined them again as we watched them torchering people and raping women i told him what he thinks is right. He didn't speak nut rushed and killed the bandits. For the next month i was explaining and he tried to teach me about the demon mark transperant world and selfless state. I told him to master it himself so he can see naturally and feel much more and then teach me so it will be more helpfull. He tought to me for 2 more months as we were heading back i heard about the virus spreding and i didn't want uto to be alone. After we reached home we saw that her parents where dying and asked me to take care of her. I told them to not worry. Then we stayed there for 10 more years. I got the mark awakened couple of years ago. I tought uto to fight demons too. I taught the insect breathing and yoriichi perfected it i introduced him to the demon slayer corps 5 years ago and i stay here to protect uto because i don't want him to be sad in this life. I was told by him to be dead to the demon slayer corps with a letter from me he was accepted. I told him that i was immortal and i was a failed test project of Muzan 500 years ago. He didn't treat me any different after i told him. He was 20 and his son was being born today he was returning from with the midwife today. I stayed by her side the whole time and the demon came but i killed him faster than slapping a mosquito. I had the demon mark i keep the transperent world always on and actively use selfless state so it was easy. I can even fight Muzan for some time till yoriichi comes in this state. I know that i cannot kill Muzan even the way i am now. It was unnecessary as yoriichi came and i told hima demon had came. He needed to kill Muzan fast or he will not be able to live with his wife and children safely he nodded witha smile and determined face. It's the first time he broke his immpassive face till now. The kid was born safely and 3 years had passed and my informant had told me that Muzan had turned a demon slayer in to a demon. I told him about it and the location Muzan traveling to. I told him fight him closer to sun rise and don't talk with him. It will give him a chance escape. I don't have to worry because i had told him all the stories and novels of underestimating and letting go of enimies. I told him if we let him go today he will go hiding after yoriichi is gone Muzan will hunt everyone related to him. He was resolute in his expression. I told him i will watch over his family and he should do what he is born to do. Yoriichi went after him. Muzan saw him attacked without a word he attacked too. Yoriichi was trained from birth for this he knew Muzan than muzan knows about him self. He knows he can defeat him but he will have the chance to escape too. So he fought it like a loosing battle he controlled every movement he and Muzan made it Muzan was going for the kill it was time the sun was rising and there is no cover yoriichi had made sure even if he explode there will be no place to hide. He used the 13 form cut out all the heart and brains but he didn't stop he continues to use every form he was trained from 2 years old. He was not allowed to do anything else but train and only after the traing can he do anything else. Every day he had to train in every form his master knows and he had to create new ones to kill Muzan for this day. His master told so many possibilities of muzan's reactions and made counter as he grew he made it so Muzan cannot respond. So he created more powerful forms. After throwing everything at him using every ounce of his strength and speed to grind Muzan to dust but still he kept going until the sun raised . He was relieved . He looked up only to see a women crying and saying thank you as she decentagrate. All the demons are dead. He is relived. He went back to his house he knows that he can live his life peacefully like he wanted. His master was outside looking proud. I saw yoriichi coming back with a smile and i knew that he succeeded. I told him i am leaving and he can rest now. He only need to teach his children to fight so they can protect themselves. I told him to create and perfect the fighting styles i tought him and i will come 50 years later to learn from him. I have tought him all the fighting styles across the world but he trained and perfected only one for killing Muzan. Now he can perfect it when he has time. I told him i will kill all the criminals as a thanks for his hard work and he can stay here. He has the Money from demon slaying and my rest of the money i had saved up all gave it to him. He understands me and i understand him

So i departed i went to many places it took less time because of superhuman speed and endurance i after 50 years i went to see him he had about a 10 year left to live. In that time he tought me everything he had and trained me as had trained him. He was now like most people expressive and wise. I stayed here until he breathed his last . For 500 years it was still traveling learning. Not just fighting i learned language dancing singing and about their culture. Before I left from Japan i tought a family of coal burners fire god dance and left. I still wanted to see tenjiro.