At 74, Iko Yamano is unattached and independent; she lives as she pleases in Tokyo. One day she gets to thinking about things she has left undone in her life. A longtime biker, she let herself be persuaded to give up the hobby five years ago, but now decides she wants to go on a “last run” road trip. Promptly purchasing all-new equipment?a bright red motorbike with the latest bells and whistles, a matching full-face helmet, and an all-black riding outfit?she sets out for the town of Kawakami in Okayama Prefecture, where her mother had grown up. Her mother died when Iko was only five years old; all she has to go by in order to identify the house is an old photograph taken when her mother was 12. Still, upon reaching Kawakami she discovers the house miraculously preserved exactly as it is in the picture. It appears to be unoccupied, and no one answers the door.
Having accomplished the first aim of her road trip, Iko turns to go, but a voice calls to her from behind. It is a little girl who looks just like the girl in the picture. She says her name is Fumiko, which was Iko’s mother’s name. Iko realizes that she is in fact her mother’s ghost, but Fumiko remains unaware of who Iko is. Fumiko seems to be visible only to Iko, not to any other living person.
Fumiko joins Iko on her road trip. As they travel together, they meet other ghosts with all sorts of different stories to tell. Iko increasingly feels a connection between the world of the living and the world of the dead. When they return to Kawakami, the old house is in the process of being torn down. Realizing it will leave Fumiko without a place to live, Iko suggests that she come with her to Tokyo.
On the way, Iko gets into a minor accident, and the motorcycle is damaged. Fumiko falls in love with the kind and handsome 20-year-old Kōki who repairs it for them?though it is of course an impossible love. Iko consoles the dejected Fumiko on the levee of the Tama River, where they pause before entering Tokyo. As they sit talking, Fumiko recounts her memories?falling in love with Iko’s father Kōsuke, and living with him and Iko and her little sister Niko in Tokyo. She has never stopped worrying about what happened to Kōsuke after she died, so is relieved to learn from Iko that he got remarried. With that load off her mind, she is ready to proceed into the next world, but Iko persuades her to stay and live with her in Tokyo instead.
They are quite the odd couple?the 74-year-old daughter and her 12-year-old, deceased mother?but Iko is satisfied both with her “last run” road trip and the new companion she has found en route.