Fuji-Hime appears in a feudal Japanese samurai-era book world within the Great Library. As princess of a bamboo fortress, her existence intertwines with the Spirit of a Japanese wisteria tree, the source of her name and mystical abilities—powers originally bestowed by Eve, an immortal guardian of the Library.

Physically mirroring Eve’s form as Hatsumi Azuma, Fuji-Hime shares identical facial features, leading Hazuki Azuma to initially confuse them. Key distinctions emerge: Fuji-Hime possesses luminous purple eyes instead of Hatsumi’s red, speaks fluently unlike Hatsumi’s typical silence in book worlds, and safeguards a treasured comb once owned by Hatsumi, hinting at deeper connections.

Her interactions with Hazuki radiate warmth and solace. She calms Hazuki’s distress over their mistaken identity by gently clasping her hand, openly declaring unwavering trust in Hazuki’s goodness. In a vulnerable moment, Fuji-Hime invites Hazuki to her chambers, cradling Hazuki’s head in her lap while tenderly stroking her hair—a deliberate echo of Hatsumi’s past comfort, revealing Fuji-Hime’s desire to occupy Hatsumi’s place in Hazuki’s heart.

Targeted by ninjas due to her enigmatic power, Fuji-Hime resolves their conflict by returning Hatsumi’s comb to Hazuki. Their parting embrace symbolizes both farewell and the comb’s generational transfer, an heirloom steeped in her world’s ancient lineage.