Nami's sudden critical illness becomes the catalyst driving the Straw Hat crew to Drum Island. Her condition worsens rapidly due to an unidentified pre-existing virus, leaving her entirely dependent on urgent medical care the crew cannot provide.

Her navigational expertise briefly surfaces early on when she detects an approaching storm, enabling defensive actions on the ship. This moment of competence sharply ends with her physical collapse, underscoring the severity of her illness. She remains incapacitated throughout the subsequent journey, requiring physical transport by crew members across hazardous terrain to reach treatment.

The quest for her cure involves overcoming hostile environmental conditions and antagonistic forces. Extreme care is taken during her mountain transport to prevent worsening her condition, limiting combat options for her carriers. Her unconscious state prevents any direct participation in conflicts or interactions on the island.

Crew relationships shape their responses: Luffy demonstrates fierce determination carrying her up the mountain, defying extreme conditions. Sanji prioritizes her safety over his own during an avalanche. Robin provides physical assistance and medical support in the avalanche aftermath, tasks originally handled by another character.

Following treatment by the island's doctors, her condition stabilizes. During recovery, she learns Chopper's backstory, forming a connection with him. This interaction contributes to Chopper's decision to join the crew, though her influence remains secondary to Luffy's. After recovering, she participates in the crew's celebratory departure with their new member.

In the 2014 special edition framing device, the entire narrative is retroactively framed as Chopper's dream. Within this context, her illness and recovery exist as dream elements, though her portrayal aligns with the primary film depiction. No expansion of her background, skills, or development beyond this storyline occurs.