Extra's Path To Demon King

After dying while trying to save his childhood friend, Tyler finds himself in a world he knows all too well, but there are some very big problems. No, it wasn’t the fact that he was an extra; in this world, it didn’t matter if you reincarnated as the main character or an insignificant extra. Steal the opportunities of the main characters and their companions? Nope, not possible. Everyone in the world ends up dying except for the two main characters, and it's unavoidable. He is literally doomed. So, what can he do? There was only one narrow path open for him to become the only other strong character that could survive the calamity, the only one greatest nemesis of the main characters, "The Demon King."