Jiyu Nanohana is a bright 14-15-year-old junior high school student sharing a close bond with her father. Her life shifts dramatically upon inheriting the Lovely Eyepatch, transforming her into the reincarnation of legendary swordsman Yagyu Jubei. This grants her masterful swordsmanship but awakens a distinct persona threatening to consume her identity. She grapples with the responsibility and fears self-erasure, especially after confronting the Ryujoji clan's centuries-old grudge.

A year later, she strives for normalcy while wrestling with guilt over Koinosuke Odago's fate. She befriends transfer student Freesia Yagyu, unaware Freesia is Yagyu Jubei's daughter and rival claimant to the Lovely Eyepatch. Despite attacks from the Siberian Yagyu clan and Freesia's aggression, Jiyu refuses to wield the eyepatch, even offering it to Freesia. Her pacifism shatters when Freesia manipulates Sai into slapping Jiyu, triggering memory confusion where Jiyu mistakes Mikage for her mother and rejects Sai.

After regaining her memories with Sai and Mikage's aid, Jiyu embraces her destiny. She provokes a duel with Freesia, revealing Freesia's spade-shaped eyepatch already holds the power she craves. Jiyu teaches Freesia the "Yagyu Shinkageryuu Mutodori" technique, cementing their reconciliation. Together, they defeat the spirit of Kita Ressai, ending the Siberian Yagyu conflict. Jiyu's journey culminates in balancing her identity as a schoolgirl and Yagyu Jubei's successor, demonstrating mature resolve without sacrificing her core self.