Benio Hanamura, a 17-year-old Tokyo schoolgirl during the Taishō era (circa 1920), was raised solely by her father, a high-ranking army official, following her mother's early death. This upbringing fostered traits defying traditional Japanese femininity: she studies kendo, drinks sake, favors Western fashions over kimono, and prioritizes literature and personal interests over housewife duties. She rejects arranged marriages and champions women's rights to careers and marrying for love.

Her closest allies are Tamaki Kitaoji, who shares Benio's advocacy for women's rights despite more traditionally feminine behavior, and Ranmaru Fujieda, a young kabuki actor whose training results in effeminate mannerisms. Benio's life shifts dramatically upon learning of her arranged engagement to Lieutenant Shinobu Ijuin, a half-German, half-Japanese officer, mandated by a pre-birth family pact. This conflicts with her principles and is complicated by Tamaki's romantic feelings for Shinobu. Benio initially refuses the match, even attempting to elope with Ranmaru, but ultimately agrees to move into the Ijuin household to learn wifely customs.

While living with the Ijuin family, Benio deliberately performs poorly at domestic tasks—ruining meals and publicly embarrassing Shinobu—hoping to end the engagement. Despite her actions, Shinobu displays genuine affection and patience, causing Benio to gradually develop reciprocal feelings. Their relationship halts when Shinobu deploys to Manchuria. After his departure, Benio cuts her waist-length hair short and seeks work to support the financially struggling Ijuin household. Failing as a geisha, she becomes a reporter for a local newspaper. Her employer, Tosei, initially exhibits misogyny but shows unexpected kindness by paying the mortgage on the Ijuin mansion.

Benio convinces Tosei to send her to Manchuria to cover the war. There, she learns Shinobu is missing and presumed dead. Overcome by grief, she attempts suicide but survives. Returning to Japan, she resolves to move forward. Later, while covering a visit by a Russian noble couple, Benio suspects the count is Shinobu. Shinobu's friend Onijima confirms her theory, revealing Shinobu suffers amnesia and believes himself married to the countess, Larissa Mikhailovna. Larissa, dying of tuberculosis and who lost her previous husband (Shinobu's half-brother), complicates matters.

Moved by Tosei paying the mortgage, Benio agrees to marry him, intending to forsake Shinobu. Meanwhile, Tamaki develops feelings for Onijima despite class differences. On Benio and Tosei's wedding day, the Great Kantō earthquake of 1923 strikes Tokyo. During the disaster, Larissa sustains fatal injuries saving Shinobu. Before dying, she reveals Shinobu's true identity and urges him to reunite with Benio. Shinobu, memories restored but severely injured, finds Benio in the wreckage. Benio chooses to remain with Shinobu despite the danger, prompting Tosei to rescue them both. In the aftermath, Benio and Shinobu marry, Tamaki follows Onijima to Manchuria, and Tosei reconciles with his past.

The 1978-1979 anime adaptation concludes differently, omitting the earthquake and later events. After Shinobu is reported missing in Siberia, Larissa finds him, mistaking him for her late husband due to his amnesia and resemblance. The anime ends with Benio reuniting with Shinobu after his memory returns, without Tosei's proposal or the earthquake sequence.

Throughout her story, Benio evolves from a rebellious tomboy rejecting societal norms to a resilient individual balancing ideals with emotional maturity. Her experiences—employment challenges, wartime reporting, and personal loss—shape her into a character reconciling feminist beliefs with deep personal commitment. Symbolic acts, like cutting her hair, underscore her transition toward self-reliance and determination.