Kaneda, a youth, develops amnesia due to trauma after coming across the corpse of his schoolmate and pal, Hiwako Shima. A mysterious patron picks him up from the medical center, and he returns to school in an attempt to recollect the events leading up to the tragedy. Adding to the confusion, his subconscious thoughts transform into a strange, surreal creature with a head resembling a crescent moon. They team up to unravel the mystery surrounding Hiwako's death.