Jigoku Shoujo -Akekazura-

Somewhere in the vast sea of the Internet, there's a website that can only be accessed at the stroke of midnight. Known as the Jigoku Tsushin, rumor has it that if you post a grudge there, the Jigoku Shoujo will appear and drag whoever torments you into the inferno. Very little is known about the girl - all we know for sure is that she lives with her equally enigmatic grandmother, that three magical straw dolls accompany and serve her, and that whenever a posting on the Jigoku Tsushin moves her, she becomes the Jigoku Shoujo.

[taken from My Anime List]