An unnamed girl residing on Sabaody Archipelago, credited simply as "Girl," possesses short orange hair, freckles, green eyes, and a notably short stature for her age. Her typical attire mirrors Nami's early look: a white-and-blue striped shirt, a dark blue miniskirt featuring a single white ring, brown gladiator sandals, and blue and yellow hair clips. She often wears red-rimmed glasses and carries a brown sling bag. Previously, she favored a green dress with a white undershirt and had longer hair. In later appearances, she adopts school-style clothing: a white shirt with a dark undershirt, dark pants, white sneakers, and a large shoulder bag.

Her personality combines bravery, determination, and a disregard for authority, specifically rejecting World Government propaganda against pirates. She openly idolizes Nami, crediting the pirate with revolutionizing her perspective. This admiration stems from Nami demonstrating that individuals without Devil Fruit powers or immense strength can attain freedom and adventure through resilience and intellect. The girl internalizes this philosophy, believing she must persistently struggle toward her goals regardless of obstacles or personal limitations.

Her story begins during the Marineford Arc, sparked by encountering Nami's wanted poster amid a crowd watching the Summit War broadcast. Deeply inspired, she spends the next two years studying the Straw Hat Pirates, collecting their wanted posters, and deducing—through flawed logic interpreting Luffy's "3D2Y" message—that the crew will reunite on Sabaody exactly two years later. She writes a heartfelt letter thanking Nami for empowering her as a "powerless girl," resolving to deliver it personally on the reunion day.

During the Return to Sabaody Arc, her mission faces repeated setbacks. Trapped in a crowd at Soul King's concert, she is struck by Perona's depression-inducing ghosts, plunging her into an hours-long emotional low. Recovering, she rushes to find the Straw Hats but collides with a young Marine brother she knows casually, dropping her letter. Mistaking it for his own vital delivery—a weapon passkey—he takes it. While retrieving her belongings with Usopp's accidental help, she sneaks into a bar where the Marine is located. She briefly retrieves the wrong envelope (containing the passkey) before becoming trapped under a table.

Overhearing Marines plan to deploy a ship-dissolving toxin against the Straw Hats, she escapes and is later saved from pirates by the Marine's older brother. Convincing him to let her witness Nami's departure by sharing her personal inspiration, they are separated by another Perona ghost attack. Captured by a hostile Marine, she realizes the toxin threat remains active. A distraction from local civilians enables her to flee barefoot to the Marine ship. There, she retrieves her actual letter from the younger Marine's bag, causing the crew to mistakenly believe she stole the passkey and chase her. Her evasion tactics delay them until the Straw Hats submerge safely. She then tears up her unread letter, revealing the passkey was never taken and is now useless.

Afterwards, she apologizes to the Marine brothers. Later, during the Punk Hazard Arc timeframe, she briefly appears conversing with a friend rescued from a tree root. Her story concludes in P.S. Fan Letter, where she wears school attire and carries a shoulder bag, indicating a return to ordinary life while retaining her admiration for Nami. Though she never meets Nami or delivers her letter, she achieves a sense of freedom by ensuring her idol's safety and witnessing the crew's departure.