Monster Hunting! Wait, She's the Savior?

Jiang Wan considers herself a half-baked demon catcher who will never amount to much! But a guy who claims to be her cousin keeps pestering her. Xie Yunzheng is a materialist who has never believed in a world of demons and monsters! That distant cousin from the marquis's household acts weak during the day and performs exorcisms at night! What is real, and what is false?