Ben no Naishi (1228-1270), a descendant of a literary branch of the Fujiwara family, created an innovative poetic account focusing on her public personae as a naishi serving at the court of Go-Fukakusa (r. 1246-1259). Traditional scholarship regards Ben no Naishi Nikki as a naive record of court minutiae written without any literary purpose, but Ben no Naishi's text is constructed consciously by her devotion to sacred and secular duties as naishi (female courtiers), who as guardians of the royal regalia--the Mirror, the Sword, and the Jewels--played vital roles in rites that legitimized and perpetuated the rule of the royal family. This translation-based study situates the text within the nikki tradition, traces the cultivation of patronage relationships that led to Ben no Naishi's job at court, delineates the sacred and secular duties of naishi, explores the unique literary aspects of the work, and reassesses Ben no Naishi's work as an innovative poetic record that subordinates the stance and contents to commemorating the reign of the royal family. The translation enhances the list of works available in English from the Kamakura literary canon.