Due to the ongoing demon rampage across the Northern Border, the two did not engage in prolonged battle.
Yan Yu took a whole night to carefully memorize all of Anna's physical characteristics. By the next evening, the two of them secretly headed northward, leaving Amur City and flying towards the vast frozen tundra under the icy skies.
The land area of the Northern Border is immense, with many uninhabited regions. In order to completely cover their tracks, the pair avoided all towns and villages along the way and eventually arrived at a certain mountain range.
According to Anna, there were mines within this mountain range, hence a lot of mining tunnels were constructed. But later, as the surface mines were depleted and deeper mining was not cost-effective, they were completely abandoned.
At the entrance to the valley, there was a small mining town, but as the mine itself was abandoned, it too became desolate and has now completely fallen to ruins, earning it the name Ghost City.
