Jigoku Shoujo S01

There is a website known as "Jigoku Tsushin" in the vast world of the internet, which is only accessible at midnight. It is said that if you mention someone you have a grudge against on that website, Jigoku Shoujo will appear and kill anyone who torments you. Very little is known about this girl. The only certain fact is that she lives with her grandmother, who is just as strange and mysterious as she is, has three magical dolls, and whenever a post is sent to the aforementioned website, she transforms into Jigoku Shoujo and begins her work.