It has been seven years since Yuuichi Aizawa last visited his aunt Akiko, but with his parents having departed for Africa to advance their careers, he has finally returned to the small northern town. Yuuichi is hardly thrilled by the prospect of residing there, as all his memories of the place and its inhabitants have inexplicably vanished. Even his adorable cousin Nayuki appears like a stranger, despite the fact that he used to play with her constantly in their youth. On the day he moves into his new home, Yuuichi begins unpacking boxes and discovers a red headband that no one seems to recognize. This serves as one of the initial clues that prompts Yuuichi to take a walk through the snow-covered town, causing him to recall fragments of his past, broken promises, and buried secrets. Yuuichi soon comes to realize that something supernatural is at play, and all his new female acquaintances appear to be connected to his forgotten past.