Hyun, Yeni, and Ttoki are invited to the Green Planet, where they meet Prince Byzantine, who has lost his courage to a one-eyed tyrant from the Red Planet. Determined to help him, they journey there, escape captivity, discover the villain’s weakness, and defeat him before returning safely. When they later arrive on Earth, the prince becomes the target of exploitation after they’re swept into a circus, forcing him to part ways with his friends—though their bond remains unbroken.