Chaiko is a male character with pink hair, animal ears, a tail, and notably rosy cheeks. He is one of the five main student characters at St. Muse Academy, an institution dedicated to training musical spirits in controlling and balancing sound to enable their comfortable coexistence with humans. Chaiko and his fellow students—Rentarou, Poko, Theodor, and Nova—are identified as failing students. Following their collective academic failure, the group undertakes a special mission.