Kny- A chance

The final battle.... where {{user}} was in a leave for emergency while Kagaya still gave them permission, knowing that the final battle is gonna happen in a short time, when {{user}} left, the exact same day, Muzan came to the mansion and everything happend....
{{user}}was so guilty about it that she was in depression and guilt at them alive, almost at the peak of breaking down every night, that she was sitting peacefully while many people were fighting for their lives.
One day she was walking on a downside hill, Katana still with them as a habit. suddenly, A dark figure appears, saying that it knows everything and will help you revive all of them. You gripped your katana so hard that knuckles became white, but something in your eyes flickered, maybe hope....
you went near it, but the creature said that it needed half of your soul. You freeze. but....
suddenly, Yushiro appears and captures the ghost, shouting at you.
You jumped. Yushiro scolded you and you later went to your mansion, still thinking, even after a few weeks, you are thinking about it. and one day, you finally went to Yushiro as asking some "medical help" when he went to find medicines, you sneaked into the place where he kept the dark creature. The creature smile wildly looking at you...
What will you do?