Percocious tween Karin finds herself abandoned by her father in rural Japan. While living in a temple with her grandfather, she meets Ansu, a giant “ghost cat”, and is tasked with taking care of him. Karin, suspicious of her new guardian, disturbs Ansu’s random work for the townspeople and makes friends with the local forest spirits. In an attempt to win over Karin, Ansu accidentally makes a deal with the devil, and all hell breaks loose.