Amanda is a young girl held captive on Pirate Zap's ship alongside her younger siblings, Milia and Holy. Her father, a professional treasure hunter, frequently left the family to pursue adventures, fostering Amanda's resentment toward treasure hunting and adventure. After her mother's death, her father continued his expeditions, intending to find treasures to bring his children happiness. Bayan fatally wounded him during one journey. Before dying, Amanda's father gifted Milia a log pose, Holy a map reading tool, and tattooed a map to a hidden treasure on Amanda's back.

Around one month before encountering the Straw Hat Pirates, Zap captured Amanda and her siblings. Imprisoned, Amanda overheard pirates Bonney and Maccus discussing their desire to escape Zap's crew but lacking funds. She proposed a deal: Bonney and Maccus could claim the treasure mapped on her back in exchange for aiding their escape. They agreed, fleeing to a deserted island via a small lifeboat.

On the island, Amanda attempted a ruse with Bonney and Maccus posing as a vacationing family when the Straw Hats arrived. She reacted angrily to Usopp's adventurous story, storming away due to lingering bitterness over her father's choices. Zap's crew soon recaptured her, and Bayan used his hypnotic choir to force her to reveal the map tattoo. During this, Bayan confessed to murdering her father.

After the Straw Hats defeated Bayan and Zap, they accompanied Amanda to locate the treasure. The island transformed into a giant clam, unveiling an enormous pearl inside. This revelation led Amanda to reconcile with her father's legacy, understanding his dream was to share wonder through discovery rather than abandon his family. Bonney and Maccus then offered to adopt Amanda and her siblings.

Amanda appeared briefly during the Pirates Festival depicted in *One Piece: Stampede*.