On a desolate Earth that has become difficult for human habitation, Itsuki, unconscious for two years because of an accident, ekes out a living on an island yet flourishing with his caretaker from childhood, Jun. While Itsuki doesn't remember what kind of accident he was in, he's fine with how things are as long as he's with his love, Jun... that is, until they have to start worrying about their dwindling resources. One day, the two of them find a mysterious machine and hear a voice from its communications device. Perhaps... there are other people still living on Earth as well. Though Itsuki is excited that the two of them can continue living together forever if they receive help, Jun's response is not so hopeful...