절망희 전야 ~The Prologue~

Materials about the "World Tree" on an ancient island are stolen from the underground library of modern wizards. An external wizard becomes the main suspect. Two wizard hunters are dispatched to return the stolen materials.
At the same time there is a normal student who transfers from school to school in attempt to run away from recurring nightmares. One day fantasy starts to interfere with the reality.
Both story-lines eventually collide in a fateful encounter, and world is brought on the brink of destruction.

[From vndbreview]