Kill the Protagonist at the Beginning and Be Picked up by the Demon King.

Katie was born again. On the first day of her rebirth, she found the young rookie Klein and stabbed him through the heart. Don't ask why. In her last life, she followed the chosen protagonist wholeheartedly, thinking that by holding on to the protagonist's halo, she could pass the level safely. But on the eve of the decisive battle, he personally slaughtered the entire team, imprisoned Katie in a dark room, and spent the only tool that could kill the hidden boss on her in a meaningless manner. The world falls into silence, and time flows back to the starting point. In this life, she decided to strike first. A system pop-up window suddenly popped up in front of me: "Do you want to bind?" She tapped "yes" with her fingertips. The next second, the system voice dropped coldly: "All functions have been deactivated." ... It pops up just for co-authorship to trick someone into registering? There is no system blessing, and there is no protagonist's aura to protect everything. Klein is dead, but the hidden final boss is still dormant in the abyss; those who are destined to go dark are still sinking step by step in their own trajectories. She originally thought that this would be a complete hell start, but a variable suddenly appeared, directly changing the hell difficulty to an easy mode. But the butterfly of fate flapped its wings one more time, causing a turbulence far beyond expectations. The runes on her back were burning hot, and there was only one sentence engraved on her back: "You will save the world." And in the background of the runes, there is also a fate that no one knows: "After you die, everything will go back to the way it was."