Jigoku Shoujo

Summary
Also known as Hell Girl or the Girl From Hell, this sinister anime series is a collection of short stories depicting the suffering of individuals who post grudges on a website accessible only at midnight, only to have their grievances avenged by an evil force.

If someone were to submit the names of the tormentor on the website, Enma Ai, the Jigoku Shoujo (Hell Girl) will offer them a black straw doll with a red string wound around its neck. If the string is pulled, she will ferry the recipient of the revenge straightaway to Hell, but on the condition that those who request her intervention rot in Hell as well at the end of their natural lives. Never knowing what paradise is like..

"O pitiful shadow bound in darkness, looking down upon others and causing them pain, a soul drowned in sinful karma... Want to try dying this once?"