Kei Watanabe is a fifth grade elementary school student. He has inherited the hunter's blood to hunt yōkai. To save the world from being destroyed, Kei Watanabe challenges a war against the yōkai.

A documentary filmmaker explores seemingly unrelated paranormal incidents connected by the legend of an ancient demon called the "kagutaba."

A young boy with a troubled home life becomes "chosen," and he stumbles into the middle of a great war of yōkai (a class of mythological creatures), where he meets a group of friendly yōkai who become his companions through his journey. Now he must fight to protect his friends and free the world of the yōkai from oppression. The yōkai originate in Japanese folklore and range from the cute and silly to the disturbing.