In of One Piece (titled "The Battle Against the Large Tiger! Who Will Be the Captain?"), the "paper" being referenced is likely the Vivre Card that Ace gives to Luffy . Key Context and Plot Details
: The brothers assist an old pirate named Naguri in building a pirate ship and eventually team up to defeat a giant tiger that had previously bested them. One Piece Episode 499
: This episode is part of the Post-War Arc , focusing on a flashback of Luffy, Ace, and Sabo's childhood in the Gray Terminal and Mt. Colubo. In of One Piece (titled "The Battle Against the Large Tiger