Natsuki isn't like other girls. She has a wand and a transformation mirror. Together with her cousin Yuu, she spends her summers dreaming of other worlds. When events threaten to part them, they make a promise. Now grown up, she survives by pretending to be normal and prepares herself for a reunion with Yuu. Will he still remember their promise? The dark and wild new novel from Sayaka Murata - author of the bestseller "Convenience Store Woman".