Once Upon a Time There Was a Demon-Sealed City

Once upon a time, there was a city like this. Outside the city, there is the invasion of monsters, the blood-stained Milky Way, and the mysterious darkness. Within the city is the will of all people, the pure land of people, and the flickering lights. That door was stained red with blood. Those people regard their lives as bricks. Not for glory and wealth, not for enlightenment and immortality. Just because when everything is over, there are thousands of lights behind you and great rivers and mountains in front of you.