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-
the conscious mind is only a 
fragment of a person's mind,
العقل الواعي هو ليس سوى جزء
،من عقل الإنسان
la mente consciente
es solo un fragmento de la mente
la mente consciente es solo
un fragmento de la mente
la zone consciente
n’est qu’un fragment de notre esprit,
la parte cosciente è solo un frammento
 della mente di una persona
a mente consciente é apenas um
fragmento da mente humana,
сознающий разум — 
лишь часть разума человека,