An insomniac is plagued by dreams of shadows

Ren, a human sleeper, has recurring dreams of traveling in darkness, accompanied by a disembodied voice. After months of this dream, the voice begins to offer him fun and freedom away from the troubles of the world. This disturbs him and he becomes resistant to his "friend," who becomes increasingly insistent. Eventually, Ren wakes from one of his dreams in terror; he refuses to sleep thereafter, despite his body and mind falling apart.