Amaumi Haruhiko is a high school student at Shimano Academy in Narasakicho, Japan. Narasakicho is home to an unexplained rainbow that perpetually overlooks the town and is associated with fulfilling a magical desire known as "Gift." Gift is a once-in-a-lifetime gift between two individuals. Haruhiko has been close to his childhood pal Kirino since he was a youngster, until he acquires a new non-blood sister named Riko. Haruhiko and Riko form a deep bond until they are forced to split ways since Haruhiko's father can no longer support the two of them. After some time has passed, Riko returns to Narasakicho and, along with Kirino, begins attending Shimano Academy alongside Haruhiko.