Whenever the kids at Sonia Obata's new school go to sleep, they go to a place called the Grand Dream. There, they can do whatever they want—play a game, write a song, or paint a masterpiece—without a single adult to bother them. But when Sonia discovers something has tampered with her memories of this place, she realizes it's not the paradise it seems to be.A mysterious girl helps Sonia escape and reveals the terrible truth: the Grand Dream is on the verge of collapse! To stop it, she gives Sonia an amulet called the Baku's Fang, which grants her the ability to travel into other dreams. She must search through the dream world, fight terrifying nightmares, and confront the traumas of her own past, in order to save her new friends. The Grand Dream won't let them go without a fight.