In a colorful island world, a cheerful figure named Mr. Sunshine appears in a commercial offering the local creatures free money in exchange for the junk his giant robots collect. Around the same time, a small red creature named Piku is woken by a ghost in a cave and told to leave. Emerging into the world, Piku finds that a legend has painted him as an evil beast, and the frightened villagers cage him until he agrees to repair the bridge he accidentally broke. As Piku earns the villagers' trust and explores further, he discovers that Mr. Sunshine's machines are quietly stripping the island of its essential resources, and he is drawn toward a small band of rebels determined to stop them.