Gwiyomi was born to a stray mother and is a brown kitten with a crescent moon mark on its forehead. When night falls, the crescent mark glows, allowing Gwiyomi to use superpowers. These powers gather moonlight to illuminate dark places, and by joining forces with Arong, Norangi, Geumdungi, and Eolgul—who possess the same abilities as Gwiyomi—they help people in danger.