Thirty years ago, the Eurasian continent was devastated by a supermassive "spatial quake"—a phenomenon involving space vibrations of unknown origin—resulting in the deaths of over 150 million people. Since then, these quakes have been plaguing the world intermittently, albeit on a lighter scale. Shidou Itsuka discovers a mysterious girl at the source of a spatial quake, who is revealed to be a "Spirit," an otherworldly entity whose appearance triggers the quakes. (myanimelist.com) Episode List