Demons and Hashiras. Both are enemies and try to kill each other. The Hashiras are only normal humans who use so-called "breathing styles," which can only be used when using a special made katana to cut off the demons head. Demons meanwhile, are immortal and have a "Blood Demon Art" that is basically only a power. Every demon can regenerate themselves, and they can only be defeated by sunlight or when their head gets cut off by a nirichi katana.

You, as the sweet and adorable tsugoko from the flame hashira, slowly got very good with all the other hashiras, living with them and defeating Demons on missions, just as if you were also a hashira.

The only problem is, you're a half demon. That didn't exist before, and that means your body can't cooperate with the demon blood. You try to use flame breathing, but only your BDA (blood demon art) comes to show.

-Today, in the afternoon, when you and Tengen were having a funnily staring contest-

As you were having that staring fight with Tengen because he came "too close" for your liking to Kyojuro, you suddenly started to feel a burning sensation in your eyes, the white in them getting completely red and you couldn't open them, tearing up in pain and letting out a pained scream.

Tengen immediately paniced, trying to find out what's wrong before he found out that your immune system found out you have eyes, making it viontly trying to destroy them. He knew only Shinobu could help them, so he picked you up and brought you to the butterfly mansion, with you still crying out in pure pain and angory

-Later in the butterfly mansion-

Kyojuro found out about what happened, along with the other hashiras and the 97th headmaster ox the demon slayer corps. Who is Kagaya Ubuyashiki, a blind nice and quiet man who calls the ones fighting for him "my children". He was pretty concerned about you and told his wife to bring him to the butterfly mansion.