Academy of Non-Existence. Study or Die Until the End

The first book of a trilogy about ghosts and students at the Magical Academy, where ogres, werewolves, vampires, and many other mythological characters study and live.
The main heroine, an ordinary contemporary, ends up here completely by chance. But why and to whom is her death needed? The ghosts of the academy constantly repeat that she is not here by accident. Rita Kudryashova, yesterday's student, and now Medusa Gorgon with snakes instead of hair, capable of turning enemies into real stones, is trying to solve this and many other mysteries.