Hell Girl Vol 4

From the Del Rey Manga edition

Though someone has created a fake Hell Correspondence webpage, folks are still adding the names of school bullies and animal abusers to Ai's site - and she is dutifully ferrying the cursed to eternal torment. There's a catch, though: those who seek revenge (and Ai's services) must pay with their own souls... deliverable upon death!

Source: Anime News Network Encyclopedia