Histoire
June, 1998: After spending two years in a coma caused by a traffic accident, Shiki Ryougi awakens with amnesia. She is visited by Touko Aozaki, a wizard and proprietor of a studio called Garan no Dou. Shiki has lost not only the memory of her accident, but also any real sense that she's even alive. Strangely, enigmatic beings begin to attack her...
Synopsis via AniList (en anglais).