Morimura Aiko is a junior high school student who is short for her age. Her father departed on a yacht ten years ago, and his whereabouts remain unknown. Her mother, a hat designer, left for Paris, leaving Aiko in the care of her uncle, Mr. Fujinami. Aiko had a pet dog named Papi, but he died in a car accident. Around the same time, another dog, Spank, appears in her life. Having endured so many unfortunate events, Aiko's life begins to brighten and she starts to smile thanks to Spank's presence.