After enduring years of torment, Kaito Sena faces death at his father's hands, only to awaken under the servitude of Elisabeth Le Fanu, the infamous Torture Princess. Bound by a church mission to vanquish demons, Kaito reluctantly aids Elisabeth, who paradoxically seeks her own demise as a true torturer. Despite her merciless nature, Kaito is drawn to her unwavering dedication. Amidst their dark journey, he grapples with the morality of granting happiness to sinners like the Torture Princess.