Jiyuu Nanohana is the main protagonist of her series, a junior high school girl who finds herself as the unwilling heir to a legendary legacy. At the start of her journey, she is an ordinary and upbeat fourteen or fifteen-year-old with a bright personality and a very close relationship with her father, Sai Nanohana. Her life takes a dramatic turn when she encounters Koinosuke Odago, a scatterbrained servant who has been searching for three hundred years for the rightful successor to the legendary swordsman Yagyu Jubei. That successor is Jiyuu, who is identified not by skill, but by her physical attributes.

Jiyuu’s role in the story is defined by the Lovely Eyepatch, an artifact that contains the spirit and combat prowess of the original Yagyu Jubei. When she places the heart-shaped eyepatch over her left eye, she transforms into Yagyu Jubei the Second, a calculated and serious swordswoman with a completely different demeanor from her usual self. While transformed, she gains masterful swordsmanship, enhanced strength, and access to the Yagyu Shinkageryu Mutodori, a technique that allows her to disarm an opponent by catching their blade with her bare hands. However, the transformation is not without cost; prolonged use of the eyepatch takes a physical toll on her, often causing a fever-like strain on her body.

Despite gaining these incredible abilities, Jiyuu’s core motivation is a profound desire for normalcy. She resists the call to be a hero and constantly tries to reject her destiny as Jubei’s successor, wishing to live as a regular schoolgirl rather than a reincarnated samurai. This internal conflict between her ordinary life and her imposed legacy is the central struggle of her character. Her reluctance only deepens after the events of her first adventure, as she carries significant guilt over the fate of Koinosuke and actively tries to forget the past.

Her father, Sai, a ghostwriter of samurai novels, remains her most steadfast support system, though their relationship is tested by the chaotic events surrounding her double life. In her second year, her desire for peace is challenged by the arrival of Freesia Yagyu, a transfer student from Russia who initially becomes her friend. Unbeknownst to Jiyuu, Freesia is the cryogenically preserved biological daughter of the original Jubei and seeks the Lovely Eyepatch as her rightful inheritance. Jiyuu, feeling unworthy and tormented by her past failures, is at first willing to surrender the eyepatch to Freesia, believing it to be the correct path.

Jiyuu’s emotional journey reaches a breaking point when Freesia manipulates her father into slapping her, causing a temporary psychological breakdown and amnesia. With the help of her father and the spiritual guide Mikage, she eventually recovers and comes to understand that she cannot run from her responsibilities. Accepting her destiny, she reclaims the Lovely Eyepatch. Her ultimate victory is not achieved through mere combat; using the Mutodori technique, she reveals that Freesia’s self-made spade-shaped eyepatch holds equal power, proving that Freesia has already achieved her goal of becoming a legitimate successor without needing to steal Jiyuu’s artifact.

By the end of her story, Jiyuu undergoes significant development, transforming from a girl who rejects her fate to one who embraces her dual identity. She comes to understand that her role as Yagyu Jubei the Second is not about perpetuating violence, but about freeing others from the chains of hatred and vengeance that have persisted for centuries. She reconciles her cheerful, everyday self with her powerful legacy, ultimately finding peace by adopting Ayunosuke, the child of her predecessor Koinosuke, thus solidifying her growth into a protector and guardian.