Jigoku Shoujo(Hell Girl)

Jigoku Shoujo, 

Known as Hell Girl in English, is an anime series currently consisting of three seasons. It has also been adapted later on into a manga series which is still ongoing, a live-action television series which has finished airing with a total of 12 episodes, and a few games and mini-games. These adaptations are not canon to the anime series and follow different storylines instead, though with core similarities to the anime.

The story of the anime(and in fact whole series) has a recurring theme of injusyice, hatred, suffering, and revenge. 
Elements like violence, harsh language, trickery, blackmail, animal cruelty, torture, insanity, twisted and complex human emotions, and such are found from time to time. Therefore, the anime is not suitable for younger audiences and viewers, and is rated R-17+.

The story revolves around a girl named Ai Enma. Her existence is known only by a small group of people, and most of these people know her instead by the name Jigoku Shoujo (Hell Girl). Something of which the existence is known of just as much would be the service that she is rumored to provide, which is also far from common knowledge. It is this service for which she is known as Jigoku Shoujo.

Ai's service consists of carrying out grudges on the behalf of the people who request her service. The means of requesting her service has changed with time, with the latest means being a website known as the Jigoku Tsuushin (Hotline to Hell). This website is once again only known by a small group of people, often in the form of urban legend. It is only accessible exactly at midnight, and can usually only be seen by those who bear significantly powerful grudges. There is very little content on the website, and it consists of only a message, a text box, and a 'send' button. If one is to receive Ai's service, they have to enter the name of the person they have a grudge against in the text box, and send it.

Ai's service consists of carrying out grudges on the behalf of the people who request her service. The means of requesting her service has changed with time, with the latest means being a website known as the Jigoku Tsuushin (Hotline to Hell). This website is once again only known by a small group of people, often in the form of urban legend. It is only accessible exactly at midnight, and can usually only be seen by those who bear significantly powerful grudges. There is very little content on the website, and it consists of only a message, a text box, and a 'send' button. If one is to receive Ai's service, they have to enter the name of the person they have a grudge against in the text box, and send it.