Travel Back in Time and Fight Monsters

After dying once, I found that the world had changed. Martial arts began to become popular, alien races from outside the territory began to attack the earth, and everything began to become strange and blurred. After rebirth, where should I go? Live an ignoble life for the rest of your life, or fight for nine days? He was reborn and practiced martial arts just for protection and survival! I shall use the talents of an immortal to fight against the calamity of the Nine Heavens! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.