One Piece (1999)

S01E32 Witch of Cocoyashi Village! Arlong's Female Leader!

After Usopp and Johnny abandon him, Zoro finds himself captured by the fishmen. Meanwhile, it's revealed that Nami had been a member of Arlong's crew all along. When a band of Fishmen launches an assault on Cocoyashi Village, Usopp steps up to defend his home and its people.