In a world where humans and youkai live together, the protagonist is a normal human boy. In his school and at home, he is surrounded by youkai, his childhood friend who hold a position of an older sister - dragon Moroha, his classmate who is a devil - Mefi, the ancient spirit fox who is the school's chairman, as well as the transfer student who also appears to have something to her. But his peaceful life started to be disrupted by disturbing dreams, which mark the change inside him.