Seoule doesn't look like a bunker at all. This made Elliot and the others wonder how much the Kkeuners have prepared for an attack like this.
The underground city was located in a gigantic hall built under he soul of the underground realm. Seungju said that the soil wasn't too hard that they easily dug through it and built this bunker in only a year.
Of course, the Eastern countries were advanced in technology. They didn't have to dig everything manually. Instead, they have machines that were capable enough to dig for them.
There were also machines that could help them with the metal frame of the bunker and machines to cement everything together. The East was much advanced and they have used every single one of their resources properly.
