Chihiro, a university student who lives a lonely life, undergoes a treatment to erase his memories in order to forget his unhappy past. However, when he awakens, his memories have not disappeared. Instead, he is left with memories of his first love with Toka, a childhood friend he has never even met. She is supposed to exist only within fabricated memories. Yet before long, Chihiro finds himself unable to get her out of his mind. But one day, Toka appears in the real world.