I am doing evil in the collapsed world

Xia was reborn from the evil but righteous sect in the Demon Realm. He returned to the city in his youth with the memories of the Demon Realm. Isn't this a perfect start to a novel?
Xia: Wait, how come there are still monsters in modern times?
Fire Moth: That's a Honkai beast.
Xia: Can you kill him?
Fire Moth: Kill them at will. The more you kill, the more famous you will become.
Xia pointed out: What happened to those monks who were possessed by demons?
Fire-Chasing Moth: A dead soldier, you can kill them at will, the more you kill, the more rewards you will get.
Xia was holding the Ten Thousand Souls Banner in his left hand and the Bloodthirsty Sword in his right hand. He was confused. He thought that after coming to the modern era, he could only continue to go to high school at Qianyu Academy, have a relationship, and apply to a medical university with his good friend Su. It was impossible for him to practice magic, but now...
Xia doubted his life: What happened? I suddenly felt like I was in the right place. Where was I? Is this still Earth?
I turned around to look at my high school classmates Mei, Kevin and Su, and looked at the map showing the eight continents and four oceans.
Xia's face was full of confusion: This is just her fault.