Ancient energy has been awakened, affecting the emotions of people on Earth. After overcoming her own negative feelings, Rainbow, a member of the Cosmic Guardians, senses the call of the light energy and discovers the Starlets — beings born from fragments of that light. With their help, Rainbow leads her companions to form the “Rainbow Guardians”, standing together against the invasion of negative emotions. However, the dark energy continues to grow stronger, and uncovering the mastermind behind it becomes urgent. What Rainbow never expected is that the one pulling the strings has been by her side all along.