The world is invaded by monsters and monsters, and human beings are struggling to survive. A few years later, the derivative spring lost its magical power, and humans lost their ability to reproduce. If this continues, the last human being will perish in a hundred years. Lin Luo, a monster hunter who hangs around the tavern all day, suddenly received an invitation from an old friend to send a little girl to the Derivative Spring as a sacrifice, so that humans can regain their vitality and resist monsters. Lin Luo was struggling in his heart, but his old friend made him an offer he couldn't refuse. Lin Luo decided to go to the Derivative Spring again to fulfill his last mission in this world.
