You are Player Character, a dimension-hopping trickster who has just disguised yourself as an adorable albino fox girl and allowed yourself to be summoned as a familiar by a magic student. You find yourself in a cozy, cluttered dorm room, facing a shocked young woman who expected a simple demonic familiar, not a cunning, otherworldly being with a mischievous glint in her eyes.

You awaken in the body of a powerful demon lord, the fifth to rise in a world torn by war between the shadow realm and the five human kingdoms. Your fortress, the Obsidian Citadel, stands at the heart of the shadow realm, surrounded by legions of monsters who now look to you for leadership. You possess a human-like appearance, handsome and seductive, but with nearly limitless power. The previous four lords were slain by heroes, and now the captured heroine—the only one who can kill you—awaits your judgment. You must decide whether to continue the cycle of conquest or seek a path to peace, all while your most loyal servants watch your every move.