Prushka, adoptive daughter of the White Whistle delver Bondrewd, was raised at the Idofront research station within the Abyss's fifth layer. Born to one of Bondrewd's Umbra Hand subordinates, she endured severe physical and psychological trauma from an early accident exposing her to the fifth layer's curse. Bondrewd intervened to prevent her euthanasia, declaring her his daughter and naming her Prushka, meaning "flower of dawn." Her recovery involved a Meinastilim creature gifted by Bondrewd, which she named Meinya and concealed in her hat. This bond marked a turning point, commemorated by Bondrewd as her new birthday. Subsequent curse exposures permanently curled her hair, yet she regained stability and matured into a cheerful, inquisitive individual.

Prushka appears as a young girl with short, curly white-and-green hair—a curse effect—and red eyes. She typically wears a green coat, gloves, and a distinctive hat resembling a delver's helmet, often accessorized with goggles and bags. After becoming a White Whistle, her form shifts to a Life Reverberating Stone resembling twisted hair with a vertical eye engraving.

Her personality blends resilience, curiosity, and unwavering devotion to Bondrewd, whom she affectionately calls "Papa." She exhibits mental fortitude by regularly exploring the fifth layer independently and deliberately challenging the curse to study its effects. Prushka forms rapid bonds, instantly befriending Riko despite limited peer exposure. She expresses a fervent desire to see the surface dawn and join Riko's adventures, values honesty, and demonstrates medical knowledge learned from Bondrewd.

During the Idofront Arc, Prushka greets Riko, Reg, and Nanachi, assists their stay, and aids their escape. Her aspiration to accompany them ends when Bondrewd transforms her into a cartridge to absorb the curse for his Blessing of the Abyss. During this process, her intense wish to journey with Riko transmutes her remains into a Life Reverberating Stone, which Riko inherits as her White Whistle.

In the Iruburu Arc, Prushka's stone travels with Riko to the sixth layer. A Narehate artisan, Poriyon, refines it into a functional White Whistle, enhancing its connection to Riko. Prushka's spirit later guides Riko to blow the whistle during crises, activating Reg's combat capabilities. Faputa reveals she orchestrated the stone's arrival to test Riko and Prushka's bond.

Prushka's abilities evolve post-transformation. As a White Whistle, she enables Riko to operate relics like the Altar of the Absolute Boundary and amplify Reg's Incinerator. She communicates telepathically with Riko, sharing sensory experiences like taste. Previously, she demonstrated resourcefulness—using Meinya's movements to navigate curse-affected stairs—and treated minor injuries using anatomical knowledge.

Relationships define her arc. Her loyalty to Bondrewd persists despite his actions, and her brief, intense friendship with Riko fuels her metamorphosis. She shares a nurturing bond with Meinya and interacts guardedly with Bondrewd's subordinates like Gueira. Post-transformation, Faputa communicates with her spirit, affirming her enduring presence.

Trivia notes her name originates from Russian "Plushka" (cinnamon bun), a misunderstanding of anatomy led to the term "Papa's Rod," and a bonus manga illustration depicts her hypothetical Blessed form. Her whistle-era outfit reflects Riko's vision of shared adventures. A song titled "Prushka" by indigo la End references her story.