[2] In 1952, she submitted her debut work, Sanjoin ki ("History of Lady Sanjo"), to the Sunday Mainichi, where it was awarded second place in that publication's 30th anniversary commemorative edition.
[6] Nagai was noted for historical novels reassessing the role of women in Japanese history, deviating from the traditional narrative.
for combining historical accuracy with translating her character's emotions into modern terms.
Likewise, in Gin no yakata ("Silver Mansion," 1980), she rehabilitated the image of Hino Tomiko (1440–1496), wife of the ineffectual shōgun Ashikaga Yoshimasa.
In 1997, NHK aired a year-long historical drama in 50 episodes, Mōri Motonari, on the life of the Sengoku-period daimyō, based on Nagai's book of the same name.