A thousand years ago, With a blood moon hanging in the sky and spatial rifts opening up, the era of monsters descended upon the world. Countless monsters ravaged the globe! Just as humanity was on the brink of complete extinction, the birth of Beast Soul Masters brought a glimmer of hope to all of mankind! With each successive generation of Beast Soul Masters inheriting and developing their skills, humanity successfully created a new civilization to combat the invasion of the monsters! Lin Yuan, in his previous life, was a top assassin who was tragically betrayed and killed by his organization. After crossing over, he became an ordinary high school student and even his contract was the weakest E-rank.