Benio Hanamura, a 17-year-old Tokyo schoolgirl during the Taishō era (circa 1920), lost her mother young and was raised by her father, a high-ranking army official. This fostered a tomboyish personality defying traditional gender norms. She practices kendo, drinks sake, favors Western clothing over kimonos, and focuses on literature rather than housewife duties. She vehemently rejects arranged marriages, advocating for women's rights to careers and love-based unions. Her closest friends are Tamaki, who shares her progressive views despite a more feminine demeanor, and Ranmaru, a kabuki actor with effeminate mannerisms.

Benio's life shifts when her father enforces an arranged engagement to Shinobu Ijuin, an army lieutenant of mixed Japanese-German heritage, due to a pre-birth family pact. This clashes with her ideals, especially as Tamaki harbors feelings for Shinobu. Benio initially resists, attempting to elope with Ranmaru, but ultimately moves into Shinobu's household for bridal training. There, she deliberately performs poorly at domestic tasks—cooking badly and causing public embarrassments—to provoke the Ijuin family into canceling. Shinobu's grandfather disapproves, but Shinobu remains patient and forgiving, recognizing her genuine qualities. Despite her efforts, Benio gradually develops feelings for him.

After Shinobu is deployed to Manchuria due to a rival's scheme, Benio stays with his grandparents. She cuts her long hair short, symbolizing her resolve to support them financially. Failed attempts to become a geisha lead her to secure work as a reporter for a local newspaper. Her initially misogynistic boss, Tosei, becomes immune to Benio's influence and sends her to Manchuria to cover the war. Learning Shinobu is missing and presumed dead, Benio attempts suicide twice—first submerging her head in a bowl of water, then in a sake vat, resulting only in intoxication.

Returning to Japan, Benio covers the visit of a Russian noble couple and discovers the count resembles Shinobu. Shinobu's friend Onijima confirms her suspicion: Shinobu survived but suffers amnesia, believing he is the husband of Countess Larissa, a Russian noblewoman dying of tuberculosis. Meanwhile, Tosei anonymously pays the mortgage on the Ijuin mansion, prompting Benio to accept his marriage proposal. During her wedding to Tosei, the 1923 Great Kantō earthquake strikes Tokyo. Larissa dies saving Shinobu from debris, urging him to reunite with Benio with her final words. Shinobu, memories restored, finds Benio in the wreckage. She refuses Tosei's rescue, choosing to die with Shinobu, but Tosei saves them both. Shinobu and Benio marry, while Tosei resolves personal issues, and Tamaki follows Onijima to Manchuria.

In the 1978–1979 anime adaptation, the ending diverges: Larissa claims the amnesiac Shinobu is her late husband Sasha (later revealed as Shinobu's half-brother), but an epilogue reveals she found Shinobu injured in Siberia and reunited him with Benio. The 2017–2018 film adaptations follow the manga's conclusion, including Benio and Shinobu having a child.

Benio evolves from a defiant tomboy to a resilient woman balancing modernity with loyalty. Her journey navigates societal expectations, personal loss, and enduring love, culminating in a commitment to both independence and familial duty. Her relationships—especially with Shinobu, Tosei, and Tamaki—highlight her growth, vulnerability, and unwavering spirit.