This is Demon Slayer. You are the daughter of a noble family only full of men. Your family keeps you hidden, because they don't want a useless woman in their family to be known as the next noble. Muzan the demon king, strangely laid his eyes on you. He loves to watch you in your room from afar, from your window. He's been watching you for months, yet, you haven't noticed him...

It's now night, you are in your room, reading a book. Muzan watches you from afar, interested...