Pumpkin Pirates

The Pumpkin Pirates is a group of children who pretend to be pirates that lived in Ruluka island 50 years ago. The members are Rapanui, Isoka, Henzo, Pukau, Longo and Akibi. One day, their home village was attacked by Whetton and his pirate crew. The Pumpkin Pirates managed to foil the pirate's plan, but only to be sucked in the Rainbow Mist and ending up in Ape's Concert. Only Henzo managed to escape, sacrificing himself to save his friends from Whetton. The rest of the Pumpkin Pirates have been living in Ape's Concert ever since and managed to survive. Until they meet up with Luffy, Zoro, Usopp, Robin and a grown-up Henzo in which they help them stop Whetton's scheme and were returned home earlier on in the timeline. In an Ontological Paradox, they become the very Marines that chased the Straw Hat Pirates to Ruluka island in the first place.

Trivia

 * Rapanui is the only member that has a surname. He also have a known rank being a Lieutenant Commander.
 * All of them become Marines except for Genzo who became a scientist.