The crew searches for the Crowning Treasure, but as they approach the island it is said to be on, they are sent into the air, separating Chopper from the group. On the island, the animals and Mobambi, a young boy living among them, declare Chopper their king. The remaining Straw Hats, searching for him, encounter the treasure hunter Butler and his henchmen. After escaping from his hoard of Horn Eaters, an armored kind of animal, the size of a cow, they succeed in finding Chopper. But when Butler notices the reindeer to be the new animal king he summons his Horn Eaters after him and the fighting starts. In an attempt to save Chopper, Mobambi loses the Crowning Treasure to Butler. Strengthened by its power, he now poses a significant threat to the Straw Hats and every animal on the island.