The Extra's Return

[You have been killed by the Hero of Light.] [You have died.] I had died at the hands of the main character in the novel I had read before. But I got another chance. I regressed and returned to the time when I first entered this novel world. Once again, I live in this novel world as an extra character. Since I have experience and knowledge, especially my World System which had upgraded, I'll do what I want to do. I will become stronger than the main character.