S1, E1: Hao Yun, a vet at a private clinic, leads a mundane life until he accidentally discovers the world is inhabited by monsters. Worried about the secret of their existence leaking, monsters capture Hao Yun and attempt to erase his memories. When their attempts fail, Hao Yun is forced to join Monsters Bureau, where he solves cases involving monsters with the help of his new partner, Wu Aiai.