We're not helping (Kny x Fem!Demon!reader x Aot)

𝑃𝑟𝑜𝑙𝑜𝑔𝑢𝑒

Long long time ago, there were demons that roamed the lands they fed off the flesh and blood of humans.

The demon lord : Muzan Kibutsuji, created demons just with his blood, the more blood a demon gets the stronger it becomes. But if your body was not strong enough then your body will die with every cell destroyed.

It is said that he has two heirs:

Unika Kibutsuji And (Y/n) Kibutsuji.

Those two are extremely powerful, it is said that they are second to power Muzan himself.
No one was thought to defeat them, but one almost did.

Yoriichi Tsugikuni

A demon slayer. More so, a demon slayer with a red blade. But Muzan only ran away like a coward. His two children followed behind him but they weren't really scared of the slayer.

(Y/n) and Unika found Yoriichi later on and talked to him, they didn't hate Slayers at all. Yoriichi was surprised, who knew the children of the demon lord was this?

And from that day on, they continued to have Secret meetings with him without Muzan knowing. Yoriichi taught them breathing techniques, how to wield a blade, etc.

Everything was good until Yoriichi's Older brother became a demon, they fought and Yoriichi lost as he was already old.

With Yoriichi's older brother becoming a demon, his brother was renamed as Kokushinbo and became Upper Moon One, while Unika and (Y/n) were Upper Moon Zero.

Unika and (Y/n) took care of Kokushinbo as they promised Yoriichi, that was the least they could do to repay him for teaching them how to wield a blade.

Kokushinbo looked up to them like older siblings, and started calling them 'Unika-nii, (Y/n)-nee, Nii-San, Nee-San, etc.

And from there on, the twelve kizuki and the demon population grew and grew. But with that, the demon slayer corps also grew, they know had ranks the highest is Hashira.

Hashiras are just like the Upper Moons, both the top ranking people in both kinds.
Lower moons were often replaced since they weren't strong, but some were lucky and made it up.

When the war started, almost all the Hashiras have died but miraculously they survived somehow. It was said they were turned into half demons instead. But they still suffered with casualties.

Muzan was weakened and there was nothing he could do, but there was one thing for sure he knew. He regretted every decision he has ever made in his life, he was just gonna give up but when he saw his heirs happy with the Slayers he joined them instead.

The next few hundred years, people among them got married and had a happy life.

But no one knew what happened when the titans started to appear, along with the few demons that got out of Muzan's control and probably multiplied.

Some say they joined the military, the scouts maybe. Some even say they lived in Wall Sina!But no one knows.

Even till this day, no one knew what happened to them.

"Wow Armin. That's one heck of a story." Eren said.

"Eren! It's not just a story! I believe they are still out there somewhere!" Armin yelled back trying to convince his friend.

"Sure Armin, whatever you say." Eren sarcastically retorted back.

———————————

Somewhere outside the walls, are a group of people or should I say demons waiting for a show to go down.

"Why are we watching again?"

"To watch what humanity would really do if titans attacked their precious walls..hehe"

-time skip to after wall maria is destroyed-

"Rui, come here."

"Yes, Nee-San?"

"I need you to go undercover inside the walls to get information."

"Ok Nee-San."

"Kokushinbo, Douma, And Akaza will go with you. We got a house in Wall Sina for you. You need to live there for two years first to get use to the environment, then go into the cadet corps to find any information ok?"

"Ok Nee-San. But how will we communicate?"

"Remember we have our link inside our minds, and the infinity fortress. Nakime will do it on that part."

"Ok Nee-San"

"One more thing, I already went over this with the rest of them. You will be changing your last name from Kibutsuji to Ayaki. Also shapeshift to make yourselves to look more human."

"Ok Nee-San, I'll miss you a lot!"

"I'll miss you to, Rui"