Dark Keigan is the covered landscape behind Soburuke. The country was before the envelop a lush and green mountain landscape. Now, the area is darkened without any sunlight to reach the few villages that are left. The villages in Dark Keigan has to rely entirely on lights to see where they are going, since the smoke avoids radiation within the visible spectrum. Due to the dark clouds, Dark Keigan have become a warm place since of the heat that stays within the light bubbles where the villages are. Dark Keigan has a province called Keigan since it is the part that is not covered in darkness, the south side of Soburuke.
The smoke that surrounds Dark Keigan seems to have a mind of its own, since it do avoids being hit by light, but if you anger the smoke long enough, for example, shining a powerful spotlight right into the dark, it will attack and destroy the device. Therefore, the villages are careful with too much light. It is dangerous to head out into the smoke without a light, since the smoke will soon enter your body through your lungs and kill you from the inside.
By advanced studies, the smoke that surrounds Dark Keigan are actually schools of tiny organisms called Svibra.