Nelly is a porcupine character with flesh-toned skin and brown quills serving as hair. She wears a purple witch hat, green scarf, pink top adorned with a crescent moon and star emblem, a pink checkerboard-patterned skirt, and pink shoes. Initially depicted as whiny and reliant on others for basic tasks, Nelly evolves into a bubbly, energetic child fueled by her aspiration to become a great wizard. Her core drive centers on spreading joy and improving the world, explicitly aiming to make everyone smile. She displays profound compassion, growing visibly distressed when witnessing unresolved conflicts. This dedication inspires her to craft enchanted castanets that induce feelings of joy and peace.

Nelly wields magical abilities including spellcasting and broom-based flight. Her journey converges with Zorori, Ishishi, and Noshishi as they unite to restore a magic forest in a magical country—a quest forming the core narrative of Season 1 of *Majime ni Fumajime Kaiketsu Zorori*. This mission involves confronting the mysterious entity Najō and seeking the Grum Rod, a potent magical artifact. When acquiring the Grum Rod, Nelly prioritizes the forest’s magical restoration over personal gain, underscoring her commitment to environmental healing.

Her powers extend to influencing plant life, hinted by an episode title referencing her as "The Flower-Blooming Girl" and aligning with a later episode involving a character who makes flowers bloom. Nelly is identified as the younger sister of Milly. Episodes like "Nelly’s Mistake" and "Rescue Nelly" place her in challenging scenarios requiring aid, reflecting her growth from dependence to proactive problem-solving within the group dynamic.