• Supernatural Invasion: After midnight, abnormal spaces appear throughout the city. Survivors call them the “Otherworld,” where every rule twists and mutates.
• Rules of Horror: Each setting has survival rules that seem reasonable but are riddled with traps. The correct rules are often hidden in the details.
• Otherworld Administration Bureau: A secret organization that controls all the rules. It uses “cleaners” to eliminate survivors who uncover the truth.
