Is It Difficult to Slay Demons?

300 Years ago, there was a global earthquake, spiritual energy revived, monsters everywhere, and humans awakened... At that time, there was a group of people who used their own flesh and blood to build a wall against monsters, in exchange for the safety of mankind for 300 years... Now there is also a group of people who guard the high walls of the city and protect the people in the city... City defenders, behind each of them are thousands of lights...