The story mainly tells about the protagonist Gokawa Shido, who lives with his sister and attends the Metropolitan Raizen High School. He lives an ordinary life and encounters a big explosion on April 10th. In the big explosion, a mysterious beautiful girl Yatogami Tohka, who is called an elf, appears. Elves are special disaster-designated life forms that exist in the neighboring world. When they appear, space shocks will occur, causing great disasters to the surrounding areas. Tohka brought a great disaster to the earth 30 years ago, and now her reappearance will bring the same disaster to the earth. However, Shido, who lives an ordinary life, can stop her from destroying the earth, that is to date her, and the story officially begins.