One Piece: Episode of Nami - Koukaishi no Namida to Nakama no Kizuna

Nami suddenly steals the Going Merry and the Straw Hats' treasure, then returns to the island ruled by the fish-man pirate Arlong. Luffy refuses to believe that the navigator who traveled beside them has simply become their enemy and follows her with Zoro, Sanji, and Usopp.

On the island, they uncover the life Nami has hidden: Arlong murdered her adoptive mother, seized her village, and forced Nami to draw maps for him while she spent years trying to buy everyone's freedom. When the bargain is cruelly destroyed, Nami finally asks Luffy for help. The Straw Hats answer by marching on Arlong Park, turning her private burden into a battle for the freedom of an entire village.