Destin for Peace (Giyu Tomioka x OC)

Chapter 10

~ Flashback ~

The gravel was smooth on the ground as you can hear the sound of the rocks hitting each other. A girl panting as she was bruised all over her body.

"One more time," she shouted as she gripped her wooden sword

"I think this is enough practice for today. You are hurting yourself too much. I'm tired," a demon slayer said putting their actual sword away and leaving the girl alone in the field

The girl laid at to ground as she stares at the clouds. 

"Woah Amaterasu that's the tenth person you knocked out," someone exclaimed

The girl rose to see that the demon slayer fell unconscious near her. She turned to the voice to see Shinobu in her demon slayer uniform

Amaterasu was ten years old and Shinobu was 9. 

"Of course I want to be so strong that demons have to worry about me. I want to protect everyone so I can never say that I didn't try," Amaterasu explained looking at her wooden sword

Shinobu sighed as she smacked Amaterasu in the head

"You have to learn when to take care of yourself. Don't worry when I'm older I would also kill demons to protect everyone," Shinobu said

Amaterasu smiled as she took Shinobu hand

"Watch I'm going to be the one to protect you. You will never have to worry about me. I'm training so hard that I will be able to defeat the head of demons," Amaterasu smirked as she picked up her sword. "Come on let's go to your sister so I can get healed."

~~~ End of Flashback ~~~

Amaterasu is in Asakusa, Tokyo as a demon lurks around the area. 

'I miss Giyu but he said he was busy with demons. He's such a buzz kill.'

Amaterasu jumps from building to building to see a whole crowd in the street

She sees Tanjiro confronting a man. She looks more closely as she can sense the dark aura around him

"Muzan Kibutsiji," she mumbled as she glares at him 

She would go up and fight him but no doubt he could be much stronger than last time

Muzan, recognizing that Tanjiro is from the Demon Slayer Corps, casually slices the neck of a passerby, turning him into a demon.

As he was slipping away he felt a shiver. He looked up the roof to see a familiar figure standing in a dark roof

Unable to see the face he felt anger as he walked away not know what Tanjiro declared

 The newly-turned demon goes on a rampage, forcing Tanjiro to subdue him and allowing Muzan to slip away. Police arrive and attempt to pull Tanjiro off. 

Amaterasu jumps down to help get the police out of Tanjiro's but he is helped by a nearby demon, Tamayo, and her companion Yushiro.

The woman reveals that she is a doctor who wishes to annihilate Kibutsuji.

"Amaterasu! I'm sorry I had to bring you into this mess," Tanjiro said bowing up and down multiple times

Amaterasu just chuckled as she put her hand on his head.

"It's fine I wasn't planning to rest anytime soon. I'm sure your sister must be waiting, we should hurry," she said rushing over the to the food truck

Utaka yells at him for not eating his Udon. Tanjiro repays him by quickly devouring two whole bowls of Udon as Amaterasu just buys one bowl. 

He apologizes to Nezuko and she notices a demon boy watching them.

 Tanjiro recognizes him as the boy with the woman earlier. The boy tells him to follow, but not after asking why he's with a demon and an "eyesore". 

"I'm going as well. I can't trust Tanjiro and Nezuko being alone with Muzan running around," Amaterasu said holding both of their hands

Yushiro glares at her and sighs

He brings Tanjiro, Amaterasu, and Nezuko to a house under a cloaking spell. Inside, Tamayo tells Tanjiro the lady from earlier is recovering fine but her husband is restrained in the basement. 

Tanjiro questions how a demon can operate on a human without wanting to feed, angering Yushiro. Tamayo calms the boy and they move into the next room away from the patient.

She explains how as every demon contains Muzan's blood, their whereabouts and movements can be tracked by him: should they mention him to anyone, their cells will be destroyed — this is called "the Kibutsuji curse". 

Tamayo reveals how after 200 years of relentless research, she has finally managed to undo Kibutsuji's curse on her and gain the ability to turn humans into demons, although this procedure is only performed on patients that are nearing the end of their lives and choose that path, Yushiro being one of them.

She has also tweaked her and Yushiro's body so that they need to survive only with a little amount of human blood, purchased as blood transfusions. 

Tanjiro agrees to work with Tamayo to develop a cure for Nezuko, promising to let her study his sister's blood and bring blood from powerful demons related closely to Muzan for her research.

Amaterasu offered to help as she hands Tamayo a blood vile. The vile contained her healing blood cell but never really explained it was her blood

Amaterasu explains that the princess had this amazing healing power ever since she was young and that her blood can heal without her physical being there.

Tamayo was amazed. So took a bit of Nezuko blood and mixed it the blood in the vile. It turned the demon blood human but most of it just turned back to humans.

Amaterasu explained that she was the only one to test the blood vile so she asked everyone to keep it a secret for the time being

Tanjiro thanked Amaterasu tearing up as he pleaded his life to her.

Amaterasu simply said

"You will always regret not doing anything so I think I'm just selfish for doing it because of my morals," she smiled as she remembers the first time she realized that she is able to try and pick up the sword.

The regrets from her past life will vanish. Even if she doesn't save that one person she at least gave it her best