Shikishima Ritsu was living a fulfilling high school life. Then one day, when Ritsu heard the new song from popular idol, μ, he noticed a cry for help hidding within the song. Ritsu tried to confirm it with his friends, but none of them would respond to his questions, and they even acted off. The suspicious incongruities continued piling up until the new year's entrance ceremonies. Yet the new students entering the school were-