Devil's High School: Kill the Protagonist at the Beginning and Activate the System

At the beginning, I didn't even have a body. Please show me the system and explain what is going on. I chose the Necromancer profession at the beginning, but why did I become the public enemy of the living? The system is so big that I won't hit you if you come out. At the beginning, Hyoudou Issei was hit by a bicycle, and half of his HP was gone. The system was so big, "Where are you, I'm going to kill you." No, today is the first day of school, and Hyoudou Issei is still an ordinary person. Then am I, hehehehehe Kill the big boss at the beginning, and the Gauntlet of the God-killing Sekiryuutei will be mine. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.