Princess Kaguya exists as a supernatural entity within the Library, intrinsically linked to the color sky blue in her visual depictions and manifestations of lifeforce. Her combat proficiency evolves across weapon types, beginning with polearms and later incorporating grimoires and exorcism tools. She wields job skills that substantially augment these specialized weapons for herself and nearby allies, alongside granting incremental stat boosts like magic attack, magic defense, physical defense, and HP at advanced levels. Village and noble testimonies offer fragmented glimpses of her. One villager voices disgust at her bamboo origins and unnatural growth, while the old man who discovered her credits the wealth brought by bamboo gold. An old woman elevates her to divine status, citing social prohibitions against mingling with commoners. These accounts reveal societal ambivalence toward her presence. Her story engages multiversal conflicts, where alternate Library versions coexist and clash as part of a greater mission: gathering lifeforce to revive their authors. This imperative forces lethal confrontations, even among her other selves. Her Reality counterpart meets a tragic end in the Act of Elimination, culminating in suicide alongside Alice, Gretel, and Little Match Girl. Her own words speak of endurance and yearning: "Please hit me with all your strength," the physical strain of "Aa... My body is throbbing...!," and the aspiration, "I hope there will be a wonderful encounter in store for me." Within the Library's cosmology, she functions as an anthropomorphic personification of an undefined abstract concept. She joins collective efforts against existential threats, forming temporary alliances during events like the transcendent trajectory anniversary and battles against Nightmares. Her Reality variant reappears in side narratives such as "It All Starts with the Stars," where altered timelines might circumvent her established fate. Her capacity to summon weapons manifests explicitly in the manga continuity, where contract-based powers enable instant armament creation during the Death Match game.