The story of different individuals that have a certain grudge access the Hell Hotline (Jigoku Tsushin) to enter the name of those they want revenge on. Enma Ai, the hell girl, takes on the revenge for them in exchange for eternity in hell after their death.

(Source: Anime News Network)

Included chapters:
Volume 3 contains the side stories "Karinui" (かりぬい) and "Sakura Uta" (さくらうた).
Volume 4 contains a prologue.
Volume 6 contains the side story "Ichimokuren" (一目連).
Volume 7 contains the side story "Kamifuusen Fuwari" (紙風船ふわり).
Volume 9 contains the side story "Yukemuri Jigoku, Tabi no Yado" (湯けむり地獄、旅の宿).