One Piece - Long Ring Long Land

The Straw Hats accidentally float down into the Marine base, G-8. Forced to abandon ship, the crew must make their way through the base to reclaim the Going Merry and avoid capture. The crew manage to safely reach their next island, Long Ring Long Land. They meet a nomad who's been stuck on the island for a while and offer to help him. But before they can, they're challenged by a pirate who calls himself Foxy the Silver Fox in a game of "Davy Back Fight", where the losers can lose their crew members. One night as the crew rest, a boy with a seahorse-shaped flute plays it near the ship. The next day the crew awaken with their memories of each other wiped out, except for Robin. It's up to her, who was the only one not affected, to get the crew's memories back and find out the cause of it. The Straw Hat pirates later re-encounter Foxy, Porche, and Hamburg. This encounter leads to a fight, and also leads to the encounter with Aokiji.