In this world, monsters and humans coexist, but once a monster does evil, it will be subdued by the demon master of the Thirteenth Bureau and seize its essence.
Qin Chuan is a delivery boy during the day and a trainee demon master who wanders around the city at night. However, he has compassion and often lets go of demons who do not commit evil on their own. Facing the thirteen rounds of assessments, he still adheres to his principles and never kills innocent demons indiscriminately.
But when he passed the exam and met all kinds of monsters, he found that the world, the Thirteen Bureaus, and himself were all different...
