|Itsuka Shido is a high school boy. After the last day of the spring holidays, school has started, but a spacequake wrecked the town and a girl in armor appears in front of him. Shido's adoptive sister, Kotori, tells him that the girl is a "Special Disasterous Designated Creature: Spirit," which causes spacequakes. Kotori discloses that she is the commander of the organization that deals with spirits, <Ratatoskr> and orders him to go out on a date with the Spirit. Kotori tells him, "I don't ask you to defeat the spirit. Just let her fall in love with you and save the world."