Realm of Black

The ROB (Realm of Black) is home to shadows and sirens.

It is located between Hell and the World of the Living.

Shadowmasters also reside here, using it as a place to escape to when needed.

The Chambers
The Chambers is the prison of all crime within the ROB.

Takeshi is one of the prisoners there, and was held in the lowest level by chains and shadow magic. He was made unable to escape, until Gin Akuma killed him to save Sakura's life.

The Portals
The Portals lead to anywhere in existence. It is used by sirens to transport to a place with convinience, making their job of slaying shadows quicker and easier.