Naoko is first seen during the 1923 Great Kanto earthquake of Japan on a train travelling with her maid. Happy, fun, and spirited, she first meets Jirō Horikoshi when she saves his hat from flying away on the breeze. As Naoko tries to rescue Jiro's hat, she almost falls from the platform of the train. But, then Jiro and her maid rescue her from going overboard.
The earthquake then causes a panic, and Naoko and her maid are in a trouble because her maid has broken her leg. Jiro walks Naoko's maid to the Naoko's house without leaving his name. Soon after, he returns to the university and then tells his younger sister, Kayo, that he tried to return to Naoko's home after the earthquake but found that her house had burned down. Naoko grows into a beautiful young woman who lives in a summer resort with her father, Satomi.
Years later, while Jiro vacations at a summer resort, he unknowingly runs into Naoko again. Jiro first spots her as he tries to keep her umbrella from blowing away. Naoko is impressed while watching him from atop of a hill while painting. That night, while having dinner with her father, Naoko comments that Jiro was the person who had saved her and her maid that day of the earthquake, but, Jiro and Naoko are both too shy to meet again. The next day, however, Jiro takes a walk and finds Naoko who comments it was like the wind had brought him to her once again. Both Jiro and Naoko fall in love and develop a happy, nurturing relationship, such as sending paper airplanes to one another. As Jiro plans to marry Naoko, he soon learns that Naoko has tuberculosis and she doesn't want to marry Jiro until she recovers. Therefore, she decides to go to a sanatorium to recover, but, cannot bear to be apart from Jiro and returns to marry him. In the house of Jiro's manager, he and his wife preform an impromptu traditional wedding. Naoko and Jiro lend support to one another until the day of Jiro's first successful fighter airplane flight.
However, Naoko's health declines and Kayo comments that Jiro's marriage will end badly because of the incurable nature of tuberculosis. Jiro argues, nevertheless, that everything he does is for Naoko. On the day of the test flight, Naoko feels well enough to take a walk and this is witnessed by Jiro's sister as a sign that Naoko wishes to spare Jiro from her death. Jiro feels a burst of wind and realizes that the burst of wind means that Naoko has died. Naoko last appears in his dream, telling him that he should live on the love, faith, and trust she has in him.
- The name Naoko means "straight" (直) (nao) and "child" (子) (ko).
- Naoko's current surname Horikoshi means "moat" (堀) (hori) and "surpass; cross over; move to; exceed; Vietnam" (越) (koshi).
- Her maiden name Satomi means "village" (里) (sato) and "to see" (見) (mi).