Aoi (24) is a hotel maid who likes to look at the rooms she cleans, imagining the kind of people who might have stayed there. One day, she discovers a receipt left carelessly in her lover's wallet. After breaking up with him for his infidelity, she goes back to her usual cleaning duties, and finds a diary left behind in one of the rooms. She wonders if the owner might possibly be her own long-lost father. Travelling to Yokohama, where the diary was written, she searches all over, but her father is nowhere to be seen and she remains in the dark about the very things she wanted to know most of all.