Ao ni, Fureru.

A high school sophomore, Ruriko Aoyama, has a prominent blue birthmark on her face and has learned to live with it without drawing attention. She avoids being treated differently by others. One day, she discovers her homeroom teacher, Kanda, has a notebook listing all her classmates with physical descriptions next to their names. Ruriko is surprised to find her own name has no entry. When she questions him, she learns Kanda has prosopagnosia, a condition that makes it difficult for him to recognize or differentiate human faces.