Is It Okay to Be Reborn and Cultivate Demons?

This is a world where humans and demons coexist. Shen Xun was a mercenary who unfortunately died during a mission. Fortunately, God favored him and he was reborn. Not only was he reborn, he also awakened the demonic system and obtained the killing demon body. There are ten levels of killing demon body. Increase the level by accumulating dead souls. Each level unlocked gives you powerful power. No matter if you are a wealthy tycoon or a world-destroying demon, I will kill you with one punch. Shen Xun believes that one day he will stand on top of the world.