Nir, a Player for Freak Scene Academy, trains to combat Earless threats using mechanized Equipment, specifically piloting the unit named Melvin. Her appearance includes blonde hair, blue eyes, and fair skin, complemented by an oversized red sweater, red and white shoes, and white-framed glasses. Character art depicts her in a large red plaid flannel over a white shirt with blue accents bearing the word "Polly," along with white shoes. Her visual design and name directly reference the rock band Nirvana and its frontman Kurt Cobain, with the "Polly" shirt nodding to a specific song.

Orphaned young, Nir faced profound loneliness and instability. At the academy, she encountered Hole, who manipulated her and introduced "Teen Spirit"—a drug used by Players to enhance performance despite risks of addiction and psychological harm. This substance intensified her self-destructive tendencies, culminating in a suicide attempt via Equipment crash.

Her narrative pivots upon meeting protagonists Echo and Mu. Initially drawn to Echo, she followed him, sought friendship, and shared her favorite academy spot. In return, Echo revealed his magnum opus, the AC30 amplifier. Nir betrayed this trust by weaponizing his amplifier in a terrorist attack against the school. Later, she saved Echo during a clash with Mu, offering only a detached "why not" as explanation. Their dynamic resembles a "terrorist sleeper cell" relationship more than genuine friendship.

Beyond the academy, Nir traveled to Londinium, delivering Melvin to mechanics Lyde and Ritchie for repairs. She reemerged during a critical conflict alongside the Neubauten sisters, joining the final battle against the Earless. Her journey reflects enduring internal conflict, as she later warned Mu about the madness threatening Players while contemplating her own fate.