Does anyone know of an anime character with theses traits?

I'm writing a fan fiction for Death Note, and I'm currently making a YouTube trailer for it. I have an OC of mine in it named Ayva, but I need a character to represent her in the trailer. The looks of the character really don't matter, since I don't really have a perfect image of what Ayva herself looks like just yet. But the character who represents her has to at least look like a young teenager, have either brown or black hair that's not too short, and has to be at least a little bit insane. Ayva is very mental, so if the character has a moment in their anime where they look either absolutely terrified or where they have a mental meltdown that would be perfect. And if you could send me a link to that particular episode that would be awesome! Thanks so much!