"This punishment is a fate that wouldn't wish upon even the likes of Zhang Jiao himself no matter the crimes he committed against the world."~ Lord Cao Cao to his cousin Xiahou Dun
This plain of reality of reality was designed by the gods before the great collapse to act as a form of prisons to punish the souls of humans for the crimes against the gods they have committed in life or for the oni that constantly escape and can't be contained in the Jigoku realm. This dimension was designed to trap the person's soul in a constant memory loop where they are trapped with illusions of the ones that were closest with in life and the individual is tormented with having to witness the death of each of their loved in unique painful winter themed ways (such as Freezing to death, hypothermia, severe frostbite , being frozen alive in a block of ice, etc) and the individual can't do anything to prevent it and words the person will meet a similar fate and the process will then restart and repeat. The fate of the oni normally means that oni is constantly suffering from starvation and frostbite or meets a gruesome fate of being cannibalized by one of their own and not being able to die destined to be a walking skeleton to forever suffer from the extreme cold and the pain of being eaten alive till they can obtain their old bodies back by consuming a human that has been imprisoned there or has accidentally came into the dimension. The only way a human can escape this plain of reality is to have balance between the body, soul, and mind and admit their wrongdoings in life and be at peace with what they have done wrong in life.