The Darklands is the realm created by the eldest deity of the three that created this universe. The Darklands is inhabited by creatures known as Dark Entities. Some are born in The Darklands, some are sent to The Darklands as punishment for their sins in their past life, and some might find themselves stuck and become Dark Entities. The reason it’s purple in this picture is because it takes place when Asuka was in charge. When a Dark Entity obtains a sacred item called the “Key to the Realm,” they are officially put in charge, and the realm’s color becomes the same color as the one holding the key.

Yeah it is very foggy sometimes