S1·E1 Conduct -Creed-

Four years had passed since Sagan's called a truce with the D2s. Music was still taboo throughout the world, and melodies ceased to be heard. Somewhere in America, which was now a wasteland, a little boy who grew up not knowing what music is hears the melody from a piano. The one playing it is a young man with black hair named Takt. And then, a deformed creature known as a D2 and a girl named Destiny, who is armed with a sword, appear as though they were lured in by the melody.