The Legend of Dark Night in Demon City

I accidentally came to a world full of monsters. There is also a girl accompanying him in the system. Being in the darkness, experiencing the pain of the demon who has lost his heart and lost himself in the dark night, let the dawn in the darkness shine with light, covering the entire city, using the power he possesses. To protect the safety of the entire city in the dark. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.