Most episodes are self-contained short stories in which the series narrates the suffering of a different individual caused by one or more antagonists. In general during each arc, the protagonists' dramas are explained in detail from the start of their grudges, through the escalation of their torment until it becomes unbearable and they resort to accessing the Hell Correspondence website. Although in general, the client gives the protagonist a chance, he or she usually ends up pulling the string on his or her doll and sending the antagonist to hell. Once they have pulled the string, before taking the antagonist to hell, Ai Enma punishes the person for his or her sins with the help of her companions.In the first season, the story soon follows a journalist named Shibata Hajime, a former blackmailer, and his daughter Tsugumi who shares a strange connection with the Hell Girl as they investigate the truth behind the Hell Girl. In the second season, a mysterious young girl from Hell, named Kikuri who is able to travel freely between Earth and the Twilight realm where Ai resides, is introduced. Later, the plot centers around Takuma Kurebayashi, a boy who is blamed by his townsfolk for causing disappearances around the town that are in reality caused by the townsfolk using the Hell Correspondence. In the third season, Kikuri returns to recruit Ai's assistants along with a yōkai named Yamawaro, who accepts an old offer from Ai to become her fourth assistant. The story follows Ai's mysterious possession of a young schoolgirl, Yuzuki Mikage.
