One Piece

Season 5, Episode 131

Episode Title: The First Patient! The Untold Story of the Rumble Ball!

Air Date: 2002-11-03

Overview:

After their adventures in Alabasta, the crew come upon another deserted island and split up tasks amongst themselves. Chopper is left in charge of guarding the ship, and he reminisces about the day he first made the rumble ball and his first patient, Dr. Kureha, while spending some time with the newest crewmember: Nico Robin.