Ruriko Aoyama is a high school girl with a blue bruise on her face due to a condition known as Nevus of Ota. She has learned to live without having to worry about the bruise. That way others won pay that much attention to it.
Ruriko meets Kanda, the new homeroom teacher at her school, but one day when seeing Kandas notes Ruriko notices that the notebook of her classmate is heavily written while hers is empty, so she goes to question Kanda.
However, Kanda suffers from Prosopagnosia, also called face blindness, a cognitive disorder of face perception that impairs the ability to recognize familiar faces, including ones own...