It is said that if someone seeks revenge, they should dig two graves—and this is especially true of those who use the Hell Correspondence website. At the stroke of midnight, this ominous web domain becomes accessible, and whoever inputs the name of their grudge will get a visit from Ai Enma, the Hell Girl. Ai explains that she will send the target's soul to hell, but the requester will also end up in hell when they die. For some, that price is far too steep; for others, where they will spend their afterlife has no bearing on their current, day-to-day hell. But one thing is certain: the Hell Girl will always be available to those in need of revenge, while she stoically performs her duty of ferrying souls into the darkness.

If you have a grudge against someone, you can access the Hell Correspondence website at the stroke of midnight, type in your grudge's name, and the Hell Girl, Ai Enma, will appear to grant your wish. However, the price for ridding yourself of such a burden is a steep one: in return for condemning the soul of your tormentor to Hell, your soul will also face eternal damnation. In her long vigil as the Hell Girl, Ai has met many willing to pay such a cost. In Jigoku Shoujo: Yoi no Togi, Ai and her enigmatic companions continue to carry out their work, ferrying soul after suffering soul into the depths of Hell. However, as of late, a mysterious girl has been following them. This strange child, unable to even remember her own identity, questions Ai about her duty as the Hell Girl. Who is this girl, and what connection does she have to Ai?

Ai Enma and her companions continue to offer their service of revenge against those who have wronged others, and the price is as steep as ever—for damning the offender to hell, the person exacting vengeance is sent to the abyss as well. As they cast soul after soul into the darkness, a new sinister force is watching them: a little girl named Kikuri. While Ai continues her duties, she meets a boy named Takuma Kurebayashi, known as the Devil's Child because of the horrific events that occur around him. Unfortunately, Takuma's reputation leads the townspeople to use him as a scapegoat for those who have been ferried off to hell. When things quickly spiral out of control, Ai must find a way to bring an end to this senseless violence, as it poses a threat to her very existence.

Following the events of Jigoku Shoujo Futakomori, Ai Enma, the Hell Girl, has disappeared. Her former companions decide to lead normal lives, until their absent mistress returns to them with a new companion, and in a way that none of them anticipated. Yuzuki Mikage is a normal schoolgirl who soon comes to understand the Hell Girl on an intimate level. During a dream-like trance in the bathtub, Ai kisses Yuzuki and possesses her. So when Yuzuki's friend decides to type in the name of their teacher in the Hell Correspondence website, Ai makes use of Yuzuki's body to accomplish her own task of ferrying the teacher's soul to hell. Yuzuki is disturbed by her new circumstances and wonders why she was chosen to continue Ai's work. Unfortunately for her, the Hell Girl and her assistants resume operation of Hell Correspondence, and she is dragged along for the ride towards hell itself.