Chiyoko Fujiwara, a celebrated actress who once graced the silver screen for the Ginei film company, agrees to partake in a retrospective interview as the company prepares to demolish its old studio. This marks her first interview in three decades following her abrupt departure from the entertainment scene. Documentarian Genya Tachibana, an ardent admirer of Chiyoko, visits her residence alongside his cameraman, Kyoji Ida. Before the interview starts, Tachibana presents Chiyoko with a small box containing an antique key. She reflects on the key's significance, noting that it "opens the most important thing," which prompts a deep introspection into her life.
Chiyoko's journey begins during the devastation of the 1923 Great Kantō earthquake, an event that tragically claimed her father's life. As a young schoolgirl, she is enlisted by Ginei's general manager to star in a government-sponsored film aimed at rallying the spirits of soldiers in the Second Sino-Japanese War. Despite her mother's strong disapproval, who envisions Chiyoko taking over the family confectionery shop after marriage, Chiyoko feels drawn to the allure of stardom. Her life takes a turn when she encounters a political dissident painter on the run from authorities, who she hides in her home’s storehouse. He ultimately flees to Manchuria to join his comrades, leaving her with the key to his art supplies box. Though she tries to reach him before he departs, she vows to reunite, a promise that resonates in Genya’s recognition of this moment from one of her films, intertwining her lived experiences with her cinematic roles.
As she recalls the film set in Manchuria, Chiyoko pursues an acting career there, hoping the artist might find her. Along the way, she meets Junichi Ōtaki, the general manager’s nephew and a budding director, alongside Ginei's leading actress, Eiko Shimao. Their filming journey leads Chiyoko to northern Manchuria, urged by a fortuneteller bribed by Eiko. However, her adventures soon take a darker turn as bandits ambush her train, transitioning the narrative to a dramatic Sengoku period setting where Chiyoko, as a princess, is tricked into consuming a cursed tea that seals her fate—"burn forever in the flames of eternal love." The progression of her search for the artist flows through various timelines and roles, showcasing her resilience, from a courtesan at the end of the Edo period to a schoolgirl thriving in the Taishō era. As fate would have it, Chiyoko discovers a portrait of herself, painted by the artist, on the remnants of her family’s store, a promise igniting her hope of reunion.
In the aftermath of World War II, Chiyoko rises to stardom yet remains haunted by the shadow of the artist. An unexpected twist occurs when Eiko secretly swipes the precious key. When questioned about its importance by the crew, a despondent Chiyoko realizes that her memories of the artist are fading, leading her to accept an ordinary life with Junichi. However, upon rediscovering the key in their home, she confronts Junichi, who had known of Eiko's ulterior motives to steal the key as a means of securing Chiyoko's affections. Eiko's jealousy of Chiyoko's innocence becomes apparent, illuminating the complexities of their intertwined lives. As Chiyoko’s quest unfolds, an elderly man—once a military policeman who pursued the artist—delivers a letter from him, prompting Chiyoko to board a train to the artist's hometown in Hokkaido, even though her pursuit yields no closure.
During the making of Chiyoko's final film, disaster strikes as an earthquake hits, bringing down the set. In a twist of fate, a young Genya, then an assistant, saves her. Haunted by the wraith’s image in her prop, Chiyoko retreats from acting, realizing she is no longer the girl the artist once adored. In the present, she sees the wraith in her reflection, coming to terms with the passage of time and her lost youth. As the interview concludes, another earthquake shakes her world, wreaking havoc on her health. On the way to the hospital, Genya reveals to Kyoji the chilling confession he received from the policeman about torturing the artist to death. In her final moments, Chiyoko expresses gratitude to Genya for rekindling her memories of the artist—stating that the key reopened those cherished thoughts. With her last breath, she affirms that regardless of whether she reunites with the artist, her heart has always belonged to the journey of love she undertook for him.
