Takeru Yagi is a student at the private high school Izumo Academy. He doesn't have any relatives and is alone in the world. Fortunately he enjoys a happy life thanks to his best friend and rival Takeshi, and his childhood friends Kotono and Asuka. One day a tremendous earthquake strikes Izumo Academy and in a flashing moment, the entire school turns into an old, eerie ruin full of hideous monsters. Narrowly surviving, Takeru and Asuka find that all the teachers and students are gone. Even his best friends Takeshi and Kotono have disappeared along with the entire town. Then, strange people wearing ancient clothes emerge out of nowhere. What on earth has happened to the peaceful campus and town? Takeru hasn't the slightest idea that this is the beginning of a fantastic adventure he couldn't begin to imagine.