The White Sun was the core of the Neo-Demon Realm, and there were several dimensions built inside it. Some of those dimensions were very small, while others were larger than High Worlds, and every single one of them had a purpose.
The surveillance and level of protection the NRAI applied to those dimensions were based on how important they were.
There was a dimension that was located exactly in the center of the White Sun. Although it was smaller than an average Low World, it was the place Zatiel Daybreak considered the most important in the entire Neo-Demon Realm. Not even the True Neo-Demon Doomsday Chamber could compare with how significant this place was for the Ancestor of the Neo-Demon race and how much it affected the plans he had for the universe and his ultimate goal.