Hamyuts Meseta acts as the Bantorra Library's Acting Director, a first-class Armed Librarian counted among its mightiest fighters alongside Mokkania. Her origins stem from a traumatic childhood abduction alongside her only friend, Chacoly Cocotte, by former Armed Librarian Makia. Subjected to inhuman experiments designed to create weapons against Ruruta Coozancoona, Chacoly was programmed to love Ruruta, while Meseta was conditioned to crave pain, death, and her own demise, instilling a lifelong quest for an opponent powerful enough to kill her.

She possesses fair skin, long dark blue hair, and red eyes. Her typical attire is a white button-up shirt featuring a small, self-embroidered bunny patch on the right breast—a design she periodically changes—paired with black pants. Her hair is usually worn down, half tied up by a large black or dark purple ribbon. Before joining the Armed Librarians, she dressed differently in youth, wearing a red blouse over a brown skirt, with plaited hair and spectacles.

Meseta displays an outwardly easy-going, fun-loving personality that often masks a cold-blooded, battle-lusting nature driven by her conditioning. Yet deeper complexities exist. Minth Chezain's "Sacred Eyes" reveal intense self-loathing at her core, thoughts resembling a void while simultaneously holding a profound wish for love. This duality surfaces in moments of fear, like facing Niniu, and in her deep, conflicted affection for Chacoly, her sole comfort during their shared torment. She shares a romantic past with fellow first-class Armed Librarian Mattalast Ballory and demonstrates fondness for rabbits and coffee.

As Acting Director, she leads the Armed Librarians through major conflicts: the assault on the Shindeki Church's ship at Arrow Coast, containing the Dragon Pneumonia outbreak orchestrated by Cigal Kulkesa, and defending against Ganbanzel Grove's monster. Her strategic choices during these events, such as destroying the Smokeship, sometimes draw internal criticism for perceived excessiveness. Her leadership culminates in the final confrontation with Library Director Ruruta Coozancoona, who awakens intending to destroy the world using "Tearless Ending."

Her primary weapon is a sling wrapped around her right wrist. Wielded with extraordinary precision and force, it can snipe targets from vast distances; her projectiles—typically rocks or pebbles—reach speeds five times the speed of sound, capable of piercing skulls or destroying structures like railroad bridges. She occasionally uses Schlumaffen, a rapier sword with automatic defense. Her signature magic, "Sensory Fibers," emits over a billion thin filaments from her back, extending up to 50 kilometers, granting remote tactile and auditory perception, effectively letting her "touch" and "hear" distant events. Storms disrupt these fibers, reducing her accuracy.

A latent power emerges against Ruruta: recalling the books of the deceased and forcing book eaters to consume unwanted books. This manifests as a temporary resurrection of fallen allies familiar to her, including Volken Macmani, who fight alongside her within Ruruta's "nonentity entrails." These resurrected individuals vanish once the conflict concludes, remaining fundamentally deceased. Makia's experiments also grant Meseta conditional immortality within Ruruta's inner world, tied to her brainwashed association of death with pleasure. Her survival there hinges on an inability to feel the necessary "feeling of loss" for true death.

Following the battle against Ruruta, the Bantorra Library is demolished. Meseta survives its end, though she no longer serves as Acting Director. Responsibility for book collection and preservation transitions to the new History Protection Bureau.