The year is 3173 in Arley. The USA has been remade into the States of Function after a long civil war. Recently, a suspicious organization called the SST came out of the blue and its purpose is unknown. When 15 year-old Risa wakes up she finds that everyone is gone. Everyone. As she runs around to find what's going on she unexpectedly finds a boy named Aspen, who she never thought she would see again. Their city still in tact, but their spirits low, they set off on an unexpected journey to try to find what happened to everyone. But is everyone really gone, or are Risa and Aspen the ones missing from everyone else's lives? They may not want to know the dark secrets that are behind the disappearances and the ominous situation...