High School DxD: Killing the Protagonist from the Start and Activating the System

From the start, I don't even have a body. What's going on? System, please show up and explain.

I chose the necromancer class from the start, so why have I become the enemy of all the living? System, come out. I won't hit you.

At the start, Hyoudou Issei hit me with his bicycle and took half my HP. System, where are you? I'm going to kill you.

Wait, today is the first day of school. Hyoudou Issei is still an ordinary person.

So does that mean I can, hehehehe...

I kill the big boss from the start, and the Sacred Gear, the Red Dragon Emperor's Gauntlet, is mine.

This novel and its characters are entirely fictional. Any resemblance to real people or events is purely coincidental. Please do not imitate.