Nono is the younger daughter of Inaba Masakatsu and his wife Yuki. She is introduced within the subplot that expands the Inaba family's story, which was created specifically for the television drama and does not appear in the original manga. Nono grows up as the sister of Tsuruchiyo, the heir to the Inaba house. When Tsuruchiyo succumbs to the redface pox after attaining manhood, Yuki follows the example of other daimyo families who have lost male heirs and forces Nono to dress as a boy. Nono is made to assume her brother's adult name, Masanori, and to present herself as the male successor of the Inaba domain. This deception is intended to preserve the family's position and avoid the political instability that would follow from openly acknowledging a female heir.

Nono initially complies with her mother's demand, even though it requires her to hide her true gender and live under a false identity. The burden of this masquerade weighs on her, but she shows a pragmatic understanding of the necessity behind it. Her personality is marked by a quiet resilience and a practical sense of duty. Unlike her mother, who clings to the hope of reuniting with her hidden husband, Nono recognizes that her father's disappearance and her brother's death cannot be undone. She urges her mother to accept reality and move forward.

When the female shogun Iemitsu publicly reveals that she is a woman and that the Tokugawa succession has been based on a similar deception, the pretext for Nono's cross-dressing collapses. With the shogun herself setting the precedent, Nono is allowed to stop pretending to be a man. She appears in women's clothing and assumes her rightful role as a female daimyo, governing the Inaba domain openly as a woman. This transition marks a significant personal development: from a girl forced into a male role by circumstance to a young woman who can claim authority in her own identity.

Nono's key relationship is with her mother Yuki, whose grief and desperation drive the family's initial deception. Nono acts as a stabilizing force within the household, tempering her mother's emotional turmoil with clear-headed realism. Her relationship with her father, Inaba Masakatsu, is distant; she never sees him after he goes into hiding as a stand-in for the dead shogun. However, she deduces his motives and respects his sacrifice. Nono's notable ability lies not in martial or political skill but in her emotional steadiness and her capacity to adapt to a rapidly changing social order. She embodies the generational shift in the gender-reversed world, where women gradually move from being hidden replacements to acknowledged leaders.