Five hundred years ago, Master Tianxuan sealed the King of Ten Thousand Demons in exchange for the prosperity of peace. However, the good times didn't last long, and cholera recurred in the originally peaceful town of Guiyuan. In order to protect justice and peace, the young monster catchers are eager to try. Qian Youdao, a young man who dreams of becoming "the world's number one master of catching monsters", stood out from the crowd. He and Yuan Xiangyi, a female "junior brother" who disguised himself as a man, did not know each other, and under the leadership of his master Ruitian, he set foot on the demon slayer Adventure journey. But with the conclusion of a strange case, they discovered an unknown and shocking secret...