Lady Sagami functions as the etiquette instructor engaged by the Bamboo Cutter to transform the protagonist into a noblewoman after the family moves to the capital. Her appearance epitomizes Heian-era aristocratic ideals: a white-painted face under heavy makeup and elaborate multi-layered kimonos. Her ankle-length straight hair reinforces this image of courtly formality.

Tasked with molding a free spirit into a refined princess, Sagami enforces strict adherence to aristocratic protocols. She drills her pupil in proper conduct, speech, and artistic pursuits like calligraphy and koto playing, actively suppressing natural emotion by correcting spontaneous laughter or exuberance as unbecoming of noble dignity. Her rigid methods clash fundamentally with her pupil's innate connection to nature and rural upbringing.

Frustration marks Sagami's tenure as her pupil consistently resists the social structures she embodies. This conflict culminates in Sagami's voluntary departure after her pupil rejects all aristocratic suitors. Declaring nothing more can be accomplished, she resigns, signaling the failure of imposed nobility to suppress individual spirit. Her final appearance is a silent, distant observer of the celestial ascension.

Her characterization embodies the constraints of Heian-era aristocratic expectations on women. Her name, "Sagami" – derived from "mutually" (相) and "imitation/copy" (模) – underscores her role in enforcing societal replication over authentic self-expression. Narratively and thematically, she highlights the conflict between institutional conformity and personal freedom.