This small OVA starts with the incident at Heavenly Host Elementary School, in which three small children were killed in the school's basement. After that, it shows what the characters did the night before the incident.
Original Work: Makoto Kedouin
Director/Supervision/Storyboard: Akira Iwanaga
Screenplay/Organization: Shōichi Satō
Key Animation Supervisor/Character Design: Masaki Takana