Niru possesses blonde hair, blue eyes, and fair skin. Her habitual attire includes an oversized red sweater, red and white shoes, and white-framed glasses. Character art depicts her in a large red plaid flannel worn over a white shirt with blue accents prominently displaying the word "Polly," paired with white shoes.

Orphaned young, Niru attended Freak Scene Academy, a school for Players, where profound loneliness and inner turmoil defined her experience. During this time, Hole exploited her vulnerability by introducing her to Teen Spirit, a drug Players used to alleviate stress. Her path shifted upon meeting Echo Rec and Mu at the academy. Initially pursuing friendship with Echo, Niru guided him to her favored spot within the school grounds and prompted him to reveal his magnum opus, the AC30 amp. This connection deteriorated when Niru orchestrated a terrorist attack on the academy using Echo’s amp, an act of betrayal stemming from her chaotic influences.

Later, Niru traveled to Londinium seeking repairs for her Equipment, Melvin, at a workshop operated by Lyde and Ritchie. During a conflict involving Mu, Niru intervened to rescue Echo from peril, characterizing her action with detached nonchalance. Her relationship with Echo defies conventional friendship, instead resembling a "terrorist sleeper cell" dynamic due to its unpredictability and underlying volatility.

Niru’s design and nomenclature pay homage to the American rock band Nirvana, specifically drawing inspiration from frontman Kurt Cobain; the text on her shirt directly references the Nirvana song "Polly."