My Japanese Name Is 小川 Ogawa (small river) 歩 Ayumu (walk, deeper meaning: walk your own way)
Most episodes are self-contained short stories in which the series narrates the suffering of a different individual caused by one or more antagonists. A website known as "Hell Correspondence" (Jigoku Tsūshin) may only be accessed at midnight by one who harbors a desire for revenge against their object of hatred. Should someone submit the name of someone against whom they bear a grudge or immense hatred, the Jigoku Shōjo (Hell Girl) will offer them a straw doll with a red string wound around its neck. If the string is pulled, she will ferry the target of the revenge straightaway to Hell. However, to do that, the client must agree to a pact wherein he/she will go to hell after their life has ended. Sometimes, Ai shows them the consequences of going to hell; there is constant pain and suffering and they will wander for eternity.
During each story, 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; however, this does not hold true for all cases. The Hell Correspondence website is accessible only at the strike of midnight at exactly 12:00, and only if the client accessing it has enough hatred inside him/her. Upon accessing, a flicker of a fire appears on screen and the a black page is displayed with the following text: "あなたの怨み、晴らします。" (which in Japanese is read, "anata no urami, harashimasu" and means "We will take revenge, on your behalf."), a text box where the grudge's object must be written, and a "送信" (Send) button. After the client's request is posted, they are visited by Enma Ai, a young red-eyed girl wearing a traditional sailor school uniform (usually the dark version used only in winter months). She hands them a straw doll, which is actually one of her assistants, with a red string tied to its neck. The straw doll may be red, black or dark blue, depending on which assistant it is (Hone-Onna, Wanyudo or Ichimoku Ren, respectively). She then tells them that if they want their vengeance to be delivered, they must remove the string from the doll, and their enemies will be immediately taken to Hell. A black crest-shaped mark will appear on the protagonists' chests after the revenge is carried out, which serves as a constant reminder that once their lives come to an end, they must give compensation for Ai's service by having their own souls also sent to Hell.
Ai is aided by her three assistants: Ichimoku Ren, a young man in modern, casual clothes who takes the form of the blue straw doll; Hone-Onna, a woman wearing a kimono with the obi (sash) tied in front which signifies she is a prostitute and takes the form of the red straw doll; and Wanyūdō, an old man wearing a hat and, at times, a red scarf, who takes the form of the black straw doll. The three are human in form until Ai requires one of them to become one of the straw dolls. Once a straw doll, they cannot revert back to their human form until the red string is released. Oftentimes, the trio conducts investigations on their client and potential clients, even without Ai's orders, in order to validate the proper client and aid Ai as their master. With the information gathered in the investigation, the trio sometimes uses this data to present a reenactment of the sins of the target on the event they are being judged, to remind them of the sins they committed against the client and sometimes offers them the chance to apologize or own up to their crimes. If they don't confess, Ai ferries them to hell. This is still debatable, however, as there are instances where victims are still ferried to Hell as they beg forgiveness or promise repentance; even then, there are instances where the victim is not presented the prospect of redemption at all.
Try to watch it... You'll be horrified.