"For example, I have seen another similar, yet completely different world, where there are no demons or Demon Hunters. There, humans are not bound to the earth; they use steel and flame to break through the sky's barrier."
"The sky's barrier?"
Heracles was startled by Lorenzo's recollection; no one had ever described the sky like that or talked about things concerning the sky.
Currently, humanity's understanding of this world remains shallow. Regarding the familiar sky above, humanity only built the first War Airship a few decades ago, heralding the start of conquest. Yet, after so many years, humans still do not know the sky's end.
Whenever a certain altitude is reached, extreme cold covers everything; the airship loses control and crashes. Over time, no one challenges that unknown place anymore.
