Monochrome lady

An unknown mysterious lady who would make the world or place all quite and black and white. Her real name is unknown, but she's 16 years old. Not one person seems to notice it and just still thinks the world is still its colorful self when it's all monochrome right now when she's around. She would mysteriously disappear when she's all done exploring the places she went, and people never seem to see her. She's like a ghost with a strange power...