"One Piece 3D: Mugiwara Chase" is a short film set in the expansive world of Eiichiro Oda's "One Piece." The story revolves around the Straw Hat Pirates, led by Monkey D. Luffy, as they embark on a high-stakes adventure to recover their stolen treasure. The narrative begins with the crew enjoying a peaceful moment on a remote island, only to have their treasure, including Luffy's iconic straw hat, stolen by a mysterious thief named Byron. Byron, a former circus performer with a grudge against the World Government, uses his agility and cunning to evade capture, setting off a frantic chase across the island.

The Straw Hat Pirates, determined to reclaim their belongings, split into smaller groups to track down Byron. Each member utilizes their unique abilities to navigate the island's diverse terrain, from dense forests to treacherous cliffs. Along the way, they encounter various obstacles, including traps set by Byron and his mechanical creations, which add a layer of tension and excitement to the pursuit. The film highlights the camaraderie and resourcefulness of the crew, with each member contributing to the mission in their own way.

As the chase intensifies, the Straw Hats eventually corner Byron, leading to a climactic showdown. Byron's backstory is revealed, shedding light on his motivations and the reasons behind his animosity toward the World Government. Despite his grievances, the Straw Hats remain focused on retrieving their treasure, culminating in a dramatic confrontation that showcases their teamwork and determination. The film concludes with the crew successfully recovering their stolen items and reflecting on the importance of their shared journey.

The main characters include Monkey D. Luffy, the rubber-powered captain of the Straw Hat Pirates; Roronoa Zoro, the skilled swordsman; Nami, the navigator; Usopp, the sharpshooter; Sanji, the chef and martial artist; Tony Tony Chopper, the reindeer doctor; Nico Robin, the archaeologist; Franky, the shipwright; and Brook, the musician. Each character plays a pivotal role in the narrative, contributing their unique skills and personalities to the adventure. Byron serves as the primary antagonist, with his acrobatic abilities and mechanical inventions posing a significant challenge to the crew. The film captures the essence of the "One Piece" universe, blending action, humor, and heartfelt moments in a concise and engaging format.