Traveling to a Hundred Years Later, Becoming Invincible from the Sword Drawing Technique

After traveling through time, it seems like I haven't worn it yet, because I'm still on Earth. But now it's a hundred years later. In 2028, a meteorite fell, leaving only ten human beings alive, ushering in an era of coexistence of warriors and monsters. Fortunately, Gu Xu activated the system. Complete tasks to gain practice points and lottery draws. "Congratulations on getting the special item: Mirror Xuanqing Gourd!" "Congratulations on obtaining the top-notch martial arts: the Nine-Character Body Protection Technique!" "Congratulations on obtaining the supreme secret: Immortal Sword Code!" "Congratulations on getting..." In the post-apocalyptic world of martial arts, cultivation is not easy. That's what everyone said… But Gu Xu refused to admit it. It's a little difficult, but it doesn't seem that difficult...