Nami and Robin discover that the true thief of their memories is not the boy, but a hypnotic seahorse named Tatsu. The seahorse steals memories to eventually become a "Sea God".
Sanji manages to kick the seahorse, which begins to release the stolen memories back to the crew. Episode Details Arc: Ocean's Dream (Filler). Original Air Date: February 27, 2005. OnePiece_Ep_223_ITA.mp4
Monkey D. Luffy, Roronoa Zoro, Nami, Nico Robin, Sanji, Tony Tony Chopper, Usopp, and the Seahorse (Tatsu). Nami and Robin discover that the true thief
For more detailed episode breakdowns, you can visit the One Piece Wiki or the IMDb page for this specific episode. Episode 223 | One Piece Wiki | Fandom Episode Details Arc: Ocean's Dream (Filler)
Luffy is forced to engage in a high-stakes duel with Zoro to stop him. During the fight, Zoro uses a powerful three-sword style move that leaves a large "X" shaped cut on Luffy's chest.
Note: While this "X" scar resembles Luffy's permanent post-timeskip scar, this specific injury is (filler) and is not how he received his permanent scar in the original manga.
The episode is part of the Italian dub broadcast, often titled "Zoro mette a nudo le zanne!" or similar variations depending on the network.