Passing through layers of defense facilities, gradually delving underground. Beneath the deep rock layers, sound transmission has become extremely slow, the temperature has risen slightly, but the surroundings have quieted down. After a while, Brand heard the sound of dripping water coming from afar. He estimated that there were at least three lines of defense near the surface, built almost like a maze. Thanks to his experience, he was able to avoid wasting time passing through there.
