Because she committed the sin of pride against God, the Great Angel Lucifer was cast into Hell and became a Fallen Angel. Also at the lowest level of Hell, the hierarchy of demons have sealed away Lucifer’s powers. Lucifer had lost everything, but along with the Demon King of Envy, Leviathan, that admires Lucifer and a high school girl she met on Earth named Totsuka Maria, she becomes the Demon King of Pride Lucifer and begins her journey to revenge on the Seven Demon Kings of Hell. A book of Revelations with the “Seven Deadly Sins” portrayed by beautiful Demon Kings is about to begin.

[Source: Crunchyroll]

Series of web shorts streamed after the broadcast of each episode.

Unaired shorts included with each of the seven Blu-ray/DVD volumes of the TV anime.

The "Seven Mortal Sins," demons from hell, have pressed forward and have started to spread their plague. Heaven is in chaos, and the angels of the "Seven Heavenly Virtues" are sent to Earth to search for a candidate to become the "true messiah."

[Source: Anime News Network]

Unaired episodes included with the Blu-ray/DVD release of the series.