In the dead of night, a mysterious website known as the Hell Correspondence becomes accessible—but only at midnight. Those consumed by vengeance can enter the name of someone they despise, and if accepted, that person will be dragged to hell by Ai Enma, the enigmatic Hell Girl. But there's a catch: the one who makes the request will also be condemned to hell after death.
Each episode unfolds as a dark morality tale, exploring the twisted emotions behind revenge, injustice, and suffering. Ai Enma, eternally youthful and eerily calm, offers a straw doll with a red string. Pulling it seals the deal. Her companions—Wanyūdō, Hone Onna, and Ichimoku Ren—assist in investigating the target and carrying out the punishment.
The series is episodic, yet gradually reveals Ai’s tragic backstory and the haunting reasons behind her role. It’s a chilling blend of supernatural horror and psychological drama, where every act of vengeance comes at a soul-shattering price.