Lucifer's Cage

The Abode of Satan, but known simply as Lucifer's Cage, and also called The Box, is a special sealed part of Hell, designed by God as a prison for Lucifer after he had rebelled against Heaven and further defied his Father by creating demonkind and corrupting mankind. The Cage housed Lucifer, at least until he broke free from it when the Apocalypse start.

It had six hundred and sixty-six seals on it, of which Rizevim broke 665. The last Seal, the death of a pure being who is yet tainted, was prevented by Team DxD and their allies. However, Trihexa's release broke the Cage anyway, allowing Lucifer to rise again.

Practically all the seals involve something that perverts the natural order, such as the rape of an angel, or a teacher killing his students.