Humanity is nearly extinct. A perpetual and deadly Rain falls on the Earth. Men known as Junkers plunder goods and artifacts from the ruins of civilization. One such Junker sneaks alone into the most dangerous of all ruins -- a 'Sarcophagus City'. In the center of this dead city, he discovers a pre-War planetarium.

Amamiya Yuuko, a mysterious girl dressed like a nun, and Himura Yuu, a mysterious gentleman who is somehow attached to the church where Yuuko first appears, are having a reunion in a church during Christmas time. Yuuko and Yuu reminisce about the past and remember events of the previous year.