Robin finds a broken Sky Poneglyph on a floating ruin. It mentions the "Fourth Ancient Weapon" (a fake-out – it’s actually a map to a lost library). Sanji protects her from Mist Serpents.
The crew lands on an island where ships fight in a gladiatorial arena. Franky enters Sunny in a non-lethal "Ship-Fu" tournament to win a rare metal needed for repairs. Brook provides music.
Luffy fights a Logia user who controls "Void Mist" (anime-only: a substance that absorbs sound and haki). Luffy wins by inflating himself and dispersing the mist with a giant sneeze. one piece episodes wiki
Zoro duels the Spade captain, who uses a sword that cuts memories. Zoro momentarily forgets Kuina, then remembers her harder, unlocking a new style: "Three-Sword Style: Oath of the Departed."
The rival captain reveals they want the "Eternal Mist Compass" to find the grave of a legendary pirate. Luffy refuses to fight for treasure. A three-way battle erupts with the island’s guardian. Robin finds a broken Sky Poneglyph on a floating ruin
A bacterial fog makes the crew sick. Chopper synthesizes a cure using the island’s rare flowers, but must fight a giant infected Sea King. Flashback to Hiriluk.
The crew finds a derelict ship flying the mark of the Spade Remnants (a rogue faction of former Baroque Works agents led by a mysterious swordsman). Zoro recognizes the sword style. The crew lands on an island where ships
A flashback episode: Jinbe recalls sailing this same route with Fisher Tiger. He must navigate the Sunny through a cursed reef while being taunted by a ghostly apparition of Arlong (hallucination).